<?xml version="1.0" encoding="UTF-8"?>

<!--XBRL Document Created with the Workiva Platform-->
<!--Copyright 2026 Workiva-->
<!--r:019c540a-9cb0-7c9d-b698-310bbc047c77,g:8a68b5e8-d9bc-4057-b1f6-ead794f175db-->
<link:linkbase xmlns:link="http://www.xbrl.org/2003/linkbase" xmlns:xlink="http://www.w3.org/1999/xlink" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://www.xbrl.org/2003/linkbase http://www.xbrl.org/2003/xbrl-linkbase-2003-12-31.xsd">
  <link:arcroleRef arcroleURI="https://xbrl.org/2023/arcrole/summation-item" xlink:type="simple" xlink:href="https://www.xbrl.org/2023/calculation-1.1.xsd#summation-item"/>
  <link:roleRef roleURI="http://www.nationalmi.com/role/CONDENSEDCONSOLIDATEDBALANCESHEETSUNAUDITED" xlink:type="simple" xlink:href="nmih-20260331.xsd#CONDENSEDCONSOLIDATEDBALANCESHEETSUNAUDITED"/>
  <link:calculationLink xlink:role="http://www.nationalmi.com/role/CONDENSEDCONSOLIDATEDBALANCESHEETSUNAUDITED" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_Liabilities_019c540a-9e2a-7aaf-ad62-137af65ac000" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_Liabilities"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SecuredDebt_019c540a-9e2a-7d25-8429-1123ea4ab28d" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_SecuredDebt"/>
    <link:calculationArc order="1" weight="1.0" xlink:arcrole="https://xbrl.org/2023/arcrole/summation-item" xlink:from="loc_us-gaap_Liabilities_019c540a-9e2a-7aaf-ad62-137af65ac000" xlink:to="loc_us-gaap_SecuredDebt_019c540a-9e2a-7d25-8429-1123ea4ab28d" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_UnearnedPremiums_019c540a-9e2a-7cb6-b635-dac5a131ca54" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_UnearnedPremiums"/>
    <link:calculationArc order="2" weight="1.0" xlink:arcrole="https://xbrl.org/2023/arcrole/summation-item" xlink:from="loc_us-gaap_Liabilities_019c540a-9e2a-7aaf-ad62-137af65ac000" xlink:to="loc_us-gaap_UnearnedPremiums_019c540a-9e2a-7cb6-b635-dac5a131ca54" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AccountsPayableAndAccruedLiabilitiesCurrentAndNoncurrent_019c540a-9e2a-7ddc-b411-a79de3d7659b" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_AccountsPayableAndAccruedLiabilitiesCurrentAndNoncurrent"/>
    <link:calculationArc order="3" weight="1.0" xlink:arcrole="https://xbrl.org/2023/arcrole/summation-item" xlink:from="loc_us-gaap_Liabilities_019c540a-9e2a-7aaf-ad62-137af65ac000" xlink:to="loc_us-gaap_AccountsPayableAndAccruedLiabilitiesCurrentAndNoncurrent_019c540a-9e2a-7ddc-b411-a79de3d7659b" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LiabilityForClaimsAndClaimsAdjustmentExpense_019c540a-9e2a-7104-854b-531625734274" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_LiabilityForClaimsAndClaimsAdjustmentExpense"/>
    <link:calculationArc order="4" weight="1.0" xlink:arcrole="https://xbrl.org/2023/arcrole/summation-item" xlink:from="loc_us-gaap_Liabilities_019c540a-9e2a-7aaf-ad62-137af65ac000" xlink:to="loc_us-gaap_LiabilityForClaimsAndClaimsAdjustmentExpense_019c540a-9e2a-7104-854b-531625734274" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DeferredIncomeTaxLiabilitiesNet_019c540a-9e2a-74db-a475-e08f987974ba" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DeferredIncomeTaxLiabilitiesNet"/>
    <link:calculationArc order="5" weight="1.0" xlink:arcrole="https://xbrl.org/2023/arcrole/summation-item" xlink:from="loc_us-gaap_Liabilities_019c540a-9e2a-7aaf-ad62-137af65ac000" xlink:to="loc_us-gaap_DeferredIncomeTaxLiabilitiesNet_019c540a-9e2a-74db-a475-e08f987974ba" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherLiabilities_019c540a-9e2a-7774-98c1-66ebc822ae2d" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_OtherLiabilities"/>
    <link:calculationArc order="6" weight="1.0" xlink:arcrole="https://xbrl.org/2023/arcrole/summation-item" xlink:from="loc_us-gaap_Liabilities_019c540a-9e2a-7aaf-ad62-137af65ac000" xlink:to="loc_us-gaap_OtherLiabilities_019c540a-9e2a-7774-98c1-66ebc822ae2d" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LiabilitiesAndStockholdersEquity_019c540a-9e2a-7b84-900f-b416298ceb3e" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_LiabilitiesAndStockholdersEquity"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_Liabilities_019c540a-9e2a-7f90-bdea-dd0075506224" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_Liabilities"/>
    <link:calculationArc order="1" weight="1.0" xlink:arcrole="https://xbrl.org/2023/arcrole/summation-item" xlink:from="loc_us-gaap_LiabilitiesAndStockholdersEquity_019c540a-9e2a-7b84-900f-b416298ceb3e" xlink:to="loc_us-gaap_Liabilities_019c540a-9e2a-7f90-bdea-dd0075506224" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CommitmentsAndContingencies_019c540a-9e2a-7a0d-841f-8e574eda64e0" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_CommitmentsAndContingencies"/>
    <link:calculationArc order="2" weight="1.0" xlink:arcrole="https://xbrl.org/2023/arcrole/summation-item" xlink:from="loc_us-gaap_LiabilitiesAndStockholdersEquity_019c540a-9e2a-7b84-900f-b416298ceb3e" xlink:to="loc_us-gaap_CommitmentsAndContingencies_019c540a-9e2a-7a0d-841f-8e574eda64e0" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StockholdersEquity_019c540a-9e2a-721f-a1e9-321d2e30aaf0" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_StockholdersEquity"/>
    <link:calculationArc order="3" weight="1.0" xlink:arcrole="https://xbrl.org/2023/arcrole/summation-item" xlink:from="loc_us-gaap_LiabilitiesAndStockholdersEquity_019c540a-9e2a-7b84-900f-b416298ceb3e" xlink:to="loc_us-gaap_StockholdersEquity_019c540a-9e2a-721f-a1e9-321d2e30aaf0" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StockholdersEquity_019c540a-9e2a-725f-b9db-efa8c2b29f6c" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_StockholdersEquity"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CommonStockValueOutstanding_019c540a-9e2a-75a6-b392-09b11b6c957e" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_CommonStockValueOutstanding"/>
    <link:calculationArc order="1" weight="1.0" xlink:arcrole="https://xbrl.org/2023/arcrole/summation-item" xlink:from="loc_us-gaap_StockholdersEquity_019c540a-9e2a-725f-b9db-efa8c2b29f6c" xlink:to="loc_us-gaap_CommonStockValueOutstanding_019c540a-9e2a-75a6-b392-09b11b6c957e" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AdditionalPaidInCapital_019c540a-9e2a-7c3e-9b52-9f17f622bcf5" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_AdditionalPaidInCapital"/>
    <link:calculationArc order="2" weight="1.0" xlink:arcrole="https://xbrl.org/2023/arcrole/summation-item" xlink:from="loc_us-gaap_StockholdersEquity_019c540a-9e2a-725f-b9db-efa8c2b29f6c" xlink:to="loc_us-gaap_AdditionalPaidInCapital_019c540a-9e2a-7c3e-9b52-9f17f622bcf5" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TreasuryStockCommonValue_019c540a-9e2a-7e98-99df-1db8c44a2288" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_TreasuryStockCommonValue"/>
    <link:calculationArc order="3" weight="-1.0" xlink:arcrole="https://xbrl.org/2023/arcrole/summation-item" xlink:from="loc_us-gaap_StockholdersEquity_019c540a-9e2a-725f-b9db-efa8c2b29f6c" xlink:to="loc_us-gaap_TreasuryStockCommonValue_019c540a-9e2a-7e98-99df-1db8c44a2288" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AccumulatedOtherComprehensiveIncomeLossNetOfTax_019c540a-9e2a-7695-8780-716f2295a4a2" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_AccumulatedOtherComprehensiveIncomeLossNetOfTax"/>
    <link:calculationArc order="4" weight="1.0" xlink:arcrole="https://xbrl.org/2023/arcrole/summation-item" xlink:from="loc_us-gaap_StockholdersEquity_019c540a-9e2a-725f-b9db-efa8c2b29f6c" xlink:to="loc_us-gaap_AccumulatedOtherComprehensiveIncomeLossNetOfTax_019c540a-9e2a-7695-8780-716f2295a4a2" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RetainedEarningsAccumulatedDeficit_019c540a-9e2a-7b8f-8959-b0e9d5495e0d" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_RetainedEarningsAccumulatedDeficit"/>
    <link:calculationArc order="5" weight="1.0" xlink:arcrole="https://xbrl.org/2023/arcrole/summation-item" xlink:from="loc_us-gaap_StockholdersEquity_019c540a-9e2a-725f-b9db-efa8c2b29f6c" xlink:to="loc_us-gaap_RetainedEarningsAccumulatedDeficit_019c540a-9e2a-7b8f-8959-b0e9d5495e0d" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_Assets_019c540a-9e2a-7913-b9b6-6ff8f5789175" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_Assets"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AvailableForSaleSecuritiesDebtSecurities_019c540a-9e2a-7c4c-a846-ab4bb431ea85" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_AvailableForSaleSecuritiesDebtSecurities"/>
    <link:calculationArc order="1" weight="1.0" xlink:arcrole="https://xbrl.org/2023/arcrole/summation-item" xlink:from="loc_us-gaap_Assets_019c540a-9e2a-7913-b9b6-6ff8f5789175" xlink:to="loc_us-gaap_AvailableForSaleSecuritiesDebtSecurities_019c540a-9e2a-7c4c-a846-ab4bb431ea85" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalents_019c540a-9e2a-7c35-bf38-94040639522f" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalents"/>
    <link:calculationArc order="2" weight="1.0" xlink:arcrole="https://xbrl.org/2023/arcrole/summation-item" xlink:from="loc_us-gaap_Assets_019c540a-9e2a-7913-b9b6-6ff8f5789175" xlink:to="loc_us-gaap_CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalents_019c540a-9e2a-7c35-bf38-94040639522f" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PremiumsReceivableAtCarryingValue_019c540a-9e2a-7dc6-a15e-ebcf4c39c301" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_PremiumsReceivableAtCarryingValue"/>
    <link:calculationArc order="3" weight="1.0" xlink:arcrole="https://xbrl.org/2023/arcrole/summation-item" xlink:from="loc_us-gaap_Assets_019c540a-9e2a-7913-b9b6-6ff8f5789175" xlink:to="loc_us-gaap_PremiumsReceivableAtCarryingValue_019c540a-9e2a-7dc6-a15e-ebcf4c39c301" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AccruedInvestmentIncomeReceivable_019c540a-9e2a-7e7d-89be-4335877cbbe9" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_AccruedInvestmentIncomeReceivable"/>
    <link:calculationArc order="4" weight="1.0" xlink:arcrole="https://xbrl.org/2023/arcrole/summation-item" xlink:from="loc_us-gaap_Assets_019c540a-9e2a-7913-b9b6-6ff8f5789175" xlink:to="loc_us-gaap_AccruedInvestmentIncomeReceivable_019c540a-9e2a-7e7d-89be-4335877cbbe9" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DeferredPolicyAcquisitionCosts_019c540a-9e2a-708a-a081-0a0cac7a02a4" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DeferredPolicyAcquisitionCosts"/>
    <link:calculationArc order="5" weight="1.0" xlink:arcrole="https://xbrl.org/2023/arcrole/summation-item" xlink:from="loc_us-gaap_Assets_019c540a-9e2a-7913-b9b6-6ff8f5789175" xlink:to="loc_us-gaap_DeferredPolicyAcquisitionCosts_019c540a-9e2a-708a-a081-0a0cac7a02a4" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PropertyPlantAndEquipmentNet_019c540a-9e2a-783d-8db1-4dc40a336d6e" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_PropertyPlantAndEquipmentNet"/>
    <link:calculationArc order="6" weight="1.0" xlink:arcrole="https://xbrl.org/2023/arcrole/summation-item" xlink:from="loc_us-gaap_Assets_019c540a-9e2a-7913-b9b6-6ff8f5789175" xlink:to="loc_us-gaap_PropertyPlantAndEquipmentNet_019c540a-9e2a-783d-8db1-4dc40a336d6e" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IntangibleAssetsNetIncludingGoodwill_019c540a-9e2a-7dd7-a955-85f6edfb4908" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_IntangibleAssetsNetIncludingGoodwill"/>
    <link:calculationArc order="7" weight="1.0" xlink:arcrole="https://xbrl.org/2023/arcrole/summation-item" xlink:from="loc_us-gaap_Assets_019c540a-9e2a-7913-b9b6-6ff8f5789175" xlink:to="loc_us-gaap_IntangibleAssetsNetIncludingGoodwill_019c540a-9e2a-7dd7-a955-85f6edfb4908" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ReinsuranceRecoverablesGross_019c540a-9e2a-7e86-895a-94701374b25d" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ReinsuranceRecoverablesGross"/>
    <link:calculationArc order="8" weight="1.0" xlink:arcrole="https://xbrl.org/2023/arcrole/summation-item" xlink:from="loc_us-gaap_Assets_019c540a-9e2a-7913-b9b6-6ff8f5789175" xlink:to="loc_us-gaap_ReinsuranceRecoverablesGross_019c540a-9e2a-7e86-895a-94701374b25d" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_nmih_PrepaidFederalIncomeTaxes_019c540a-9e2a-7dfd-bf0e-1c10eeb814c0" xlink:href="nmih-20260331.xsd#nmih_PrepaidFederalIncomeTaxes"/>
    <link:calculationArc order="9" weight="1.0" xlink:arcrole="https://xbrl.org/2023/arcrole/summation-item" xlink:from="loc_us-gaap_Assets_019c540a-9e2a-7913-b9b6-6ff8f5789175" xlink:to="loc_nmih_PrepaidFederalIncomeTaxes_019c540a-9e2a-7dfd-bf0e-1c10eeb814c0" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherAssets_019c540a-9e2a-71c5-a5d3-1c66e0b32cd0" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_OtherAssets"/>
    <link:calculationArc order="10" weight="1.0" xlink:arcrole="https://xbrl.org/2023/arcrole/summation-item" xlink:from="loc_us-gaap_Assets_019c540a-9e2a-7913-b9b6-6ff8f5789175" xlink:to="loc_us-gaap_OtherAssets_019c540a-9e2a-71c5-a5d3-1c66e0b32cd0" xlink:type="arc"/>
  </link:calculationLink>
  <link:roleRef roleURI="http://www.nationalmi.com/role/CONDENSEDCONSOLIDATEDSTATEMENTSOFOPERATIONSANDCOMPREHENSIVEINCOMEUNAUDITED" xlink:type="simple" xlink:href="nmih-20260331.xsd#CONDENSEDCONSOLIDATEDSTATEMENTSOFOPERATIONSANDCOMPREHENSIVEINCOMEUNAUDITED"/>
  <link:calculationLink xlink:role="http://www.nationalmi.com/role/CONDENSEDCONSOLIDATEDSTATEMENTSOFOPERATIONSANDCOMPREHENSIVEINCOMEUNAUDITED" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ComprehensiveIncomeNetOfTax_019c540a-9e2a-7016-80d9-a71de7a85b6c" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ComprehensiveIncomeNetOfTax"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NetIncomeLoss_019c540a-9e2a-7ee3-b342-87597b899d21" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_NetIncomeLoss"/>
    <link:calculationArc order="1" weight="1.0" xlink:arcrole="https://xbrl.org/2023/arcrole/summation-item" xlink:from="loc_us-gaap_ComprehensiveIncomeNetOfTax_019c540a-9e2a-7016-80d9-a71de7a85b6c" xlink:to="loc_us-gaap_NetIncomeLoss_019c540a-9e2a-7ee3-b342-87597b899d21" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherComprehensiveIncomeLossNetOfTaxPortionAttributableToParent_019c540a-9e2a-74cd-8dbd-e8083c68da4c" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_OtherComprehensiveIncomeLossNetOfTaxPortionAttributableToParent"/>
    <link:calculationArc order="2" weight="1.0" xlink:arcrole="https://xbrl.org/2023/arcrole/summation-item" xlink:from="loc_us-gaap_ComprehensiveIncomeNetOfTax_019c540a-9e2a-7016-80d9-a71de7a85b6c" xlink:to="loc_us-gaap_OtherComprehensiveIncomeLossNetOfTaxPortionAttributableToParent_019c540a-9e2a-74cd-8dbd-e8083c68da4c" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CostsAndExpenses_019c540a-9e2a-7407-8a9b-1a0325b6e131" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_CostsAndExpenses"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PolicyholderBenefitsAndClaimsIncurredNet_019c540a-9e2a-7b45-99f1-ea2f87b6e538" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_PolicyholderBenefitsAndClaimsIncurredNet"/>
    <link:calculationArc order="1" weight="1.0" xlink:arcrole="https://xbrl.org/2023/arcrole/summation-item" xlink:from="loc_us-gaap_CostsAndExpenses_019c540a-9e2a-7407-8a9b-1a0325b6e131" xlink:to="loc_us-gaap_PolicyholderBenefitsAndClaimsIncurredNet_019c540a-9e2a-7b45-99f1-ea2f87b6e538" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherCostAndExpenseOperating_019c540a-9e2a-7e16-96e6-1b0468518be7" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_OtherCostAndExpenseOperating"/>
    <link:calculationArc order="2" weight="1.0" xlink:arcrole="https://xbrl.org/2023/arcrole/summation-item" xlink:from="loc_us-gaap_CostsAndExpenses_019c540a-9e2a-7407-8a9b-1a0325b6e131" xlink:to="loc_us-gaap_OtherCostAndExpenseOperating_019c540a-9e2a-7e16-96e6-1b0468518be7" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherNonoperatingExpense_019c540a-9e2a-7053-9517-acc2f914fc69" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_OtherNonoperatingExpense"/>
    <link:calculationArc order="3" weight="1.0" xlink:arcrole="https://xbrl.org/2023/arcrole/summation-item" xlink:from="loc_us-gaap_CostsAndExpenses_019c540a-9e2a-7407-8a9b-1a0325b6e131" xlink:to="loc_us-gaap_OtherNonoperatingExpense_019c540a-9e2a-7053-9517-acc2f914fc69" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_InterestExpenseNonoperating_019c540a-9e2a-7b57-b987-1168b0061646" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_InterestExpenseNonoperating"/>
    <link:calculationArc order="4" weight="1.0" xlink:arcrole="https://xbrl.org/2023/arcrole/summation-item" xlink:from="loc_us-gaap_CostsAndExpenses_019c540a-9e2a-7407-8a9b-1a0325b6e131" xlink:to="loc_us-gaap_InterestExpenseNonoperating_019c540a-9e2a-7b57-b987-1168b0061646" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeLossFromContinuingOperationsBeforeIncomeTaxesExtraordinaryItemsNoncontrollingInterest_019c540a-9e2a-76dc-a376-9c145088397a" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_IncomeLossFromContinuingOperationsBeforeIncomeTaxesExtraordinaryItemsNoncontrollingInterest"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_Revenues_019c540a-9e2a-700d-975d-709ec3b09567" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_Revenues"/>
    <link:calculationArc order="1" weight="1.0" xlink:arcrole="https://xbrl.org/2023/arcrole/summation-item" xlink:from="loc_us-gaap_IncomeLossFromContinuingOperationsBeforeIncomeTaxesExtraordinaryItemsNoncontrollingInterest_019c540a-9e2a-76dc-a376-9c145088397a" xlink:to="loc_us-gaap_Revenues_019c540a-9e2a-700d-975d-709ec3b09567" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CostsAndExpenses_019c540a-9e2a-76a0-a773-3b9f4652f545" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_CostsAndExpenses"/>
    <link:calculationArc order="2" weight="-1.0" xlink:arcrole="https://xbrl.org/2023/arcrole/summation-item" xlink:from="loc_us-gaap_IncomeLossFromContinuingOperationsBeforeIncomeTaxesExtraordinaryItemsNoncontrollingInterest_019c540a-9e2a-76dc-a376-9c145088397a" xlink:to="loc_us-gaap_CostsAndExpenses_019c540a-9e2a-76a0-a773-3b9f4652f545" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_Revenues_019c540a-9e2a-74e8-8d23-6e59eda53b74" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_Revenues"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PremiumsEarnedNet_019c540a-9e2a-72ef-bc8f-79ea7219db37" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_PremiumsEarnedNet"/>
    <link:calculationArc order="1" weight="1.0" xlink:arcrole="https://xbrl.org/2023/arcrole/summation-item" xlink:from="loc_us-gaap_Revenues_019c540a-9e2a-74e8-8d23-6e59eda53b74" xlink:to="loc_us-gaap_PremiumsEarnedNet_019c540a-9e2a-72ef-bc8f-79ea7219db37" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NetInvestmentIncome_019c540a-9e2a-7721-ab4d-369f0c28d3a4" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_NetInvestmentIncome"/>
    <link:calculationArc order="2" weight="1.0" xlink:arcrole="https://xbrl.org/2023/arcrole/summation-item" xlink:from="loc_us-gaap_Revenues_019c540a-9e2a-74e8-8d23-6e59eda53b74" xlink:to="loc_us-gaap_NetInvestmentIncome_019c540a-9e2a-7721-ab4d-369f0c28d3a4" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_GainLossOnInvestments_019c540a-9e2a-7d94-b210-1821bbad1194" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_GainLossOnInvestments"/>
    <link:calculationArc order="3" weight="1.0" xlink:arcrole="https://xbrl.org/2023/arcrole/summation-item" xlink:from="loc_us-gaap_Revenues_019c540a-9e2a-74e8-8d23-6e59eda53b74" xlink:to="loc_us-gaap_GainLossOnInvestments_019c540a-9e2a-7d94-b210-1821bbad1194" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherIncome_019c540a-9e2a-73dc-9919-f1a1b3a7053a" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_OtherIncome"/>
    <link:calculationArc order="4" weight="1.0" xlink:arcrole="https://xbrl.org/2023/arcrole/summation-item" xlink:from="loc_us-gaap_Revenues_019c540a-9e2a-74e8-8d23-6e59eda53b74" xlink:to="loc_us-gaap_OtherIncome_019c540a-9e2a-73dc-9919-f1a1b3a7053a" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherComprehensiveIncomeLossNetOfTaxPortionAttributableToParent_019c540a-9e2a-7bee-a264-e4df828c9a01" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_OtherComprehensiveIncomeLossNetOfTaxPortionAttributableToParent"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherComprehensiveIncomeUnrealizedHoldingGainLossOnSecuritiesArisingDuringPeriodNetOfTax_019c540a-9e2a-74d3-a572-1e259354bb15" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_OtherComprehensiveIncomeUnrealizedHoldingGainLossOnSecuritiesArisingDuringPeriodNetOfTax"/>
    <link:calculationArc order="1" weight="1.0" xlink:arcrole="https://xbrl.org/2023/arcrole/summation-item" xlink:from="loc_us-gaap_OtherComprehensiveIncomeLossNetOfTaxPortionAttributableToParent_019c540a-9e2a-7bee-a264-e4df828c9a01" xlink:to="loc_us-gaap_OtherComprehensiveIncomeUnrealizedHoldingGainLossOnSecuritiesArisingDuringPeriodNetOfTax_019c540a-9e2a-74d3-a572-1e259354bb15" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherComprehensiveIncomeLossReclassificationAdjustmentFromAOCIForSaleOfSecuritiesNetOfTax_019c540a-9e2a-79fd-a34c-27653ae170ed" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_OtherComprehensiveIncomeLossReclassificationAdjustmentFromAOCIForSaleOfSecuritiesNetOfTax"/>
    <link:calculationArc order="2" weight="-1.0" xlink:arcrole="https://xbrl.org/2023/arcrole/summation-item" xlink:from="loc_us-gaap_OtherComprehensiveIncomeLossNetOfTaxPortionAttributableToParent_019c540a-9e2a-7bee-a264-e4df828c9a01" xlink:to="loc_us-gaap_OtherComprehensiveIncomeLossReclassificationAdjustmentFromAOCIForSaleOfSecuritiesNetOfTax_019c540a-9e2a-79fd-a34c-27653ae170ed" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NetIncomeLoss_019c540a-9e2a-7690-917e-3ebb0c911bc3" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_NetIncomeLoss"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeLossFromContinuingOperationsBeforeIncomeTaxesExtraordinaryItemsNoncontrollingInterest_019c540a-9e2a-7313-9939-5b5880ce08ed" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_IncomeLossFromContinuingOperationsBeforeIncomeTaxesExtraordinaryItemsNoncontrollingInterest"/>
    <link:calculationArc order="1" weight="1.0" xlink:arcrole="https://xbrl.org/2023/arcrole/summation-item" xlink:from="loc_us-gaap_NetIncomeLoss_019c540a-9e2a-7690-917e-3ebb0c911bc3" xlink:to="loc_us-gaap_IncomeLossFromContinuingOperationsBeforeIncomeTaxesExtraordinaryItemsNoncontrollingInterest_019c540a-9e2a-7313-9939-5b5880ce08ed" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeTaxExpenseBenefit_019c540a-9e2a-72c7-b5d6-54496073e817" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_IncomeTaxExpenseBenefit"/>
    <link:calculationArc order="2" weight="-1.0" xlink:arcrole="https://xbrl.org/2023/arcrole/summation-item" xlink:from="loc_us-gaap_NetIncomeLoss_019c540a-9e2a-7690-917e-3ebb0c911bc3" xlink:to="loc_us-gaap_IncomeTaxExpenseBenefit_019c540a-9e2a-72c7-b5d6-54496073e817" xlink:type="arc"/>
  </link:calculationLink>
  <link:roleRef roleURI="http://www.nationalmi.com/role/CONDENSEDCONSOLIDATEDSTATEMENTSOFCASHFLOWSUNAUDITED" xlink:type="simple" xlink:href="nmih-20260331.xsd#CONDENSEDCONSOLIDATEDSTATEMENTSOFCASHFLOWSUNAUDITED"/>
  <link:calculationLink xlink:role="http://www.nationalmi.com/role/CONDENSEDCONSOLIDATEDSTATEMENTSOFCASHFLOWSUNAUDITED" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalentsPeriodIncreaseDecreaseIncludingExchangeRateEffect_019c540a-9e2a-74cf-8d29-45a03fd3f465" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalentsPeriodIncreaseDecreaseIncludingExchangeRateEffect"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NetCashProvidedByUsedInOperatingActivities_019c540a-9e2a-71a8-a3e1-f3bdfb2cc57e" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_NetCashProvidedByUsedInOperatingActivities"/>
    <link:calculationArc order="1" weight="1.0" xlink:arcrole="https://xbrl.org/2023/arcrole/summation-item" xlink:from="loc_us-gaap_CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalentsPeriodIncreaseDecreaseIncludingExchangeRateEffect_019c540a-9e2a-74cf-8d29-45a03fd3f465" xlink:to="loc_us-gaap_NetCashProvidedByUsedInOperatingActivities_019c540a-9e2a-71a8-a3e1-f3bdfb2cc57e" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NetCashProvidedByUsedInInvestingActivities_019c540a-9e2a-7be1-9fed-8846e8f52b32" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_NetCashProvidedByUsedInInvestingActivities"/>
    <link:calculationArc order="2" weight="1.0" xlink:arcrole="https://xbrl.org/2023/arcrole/summation-item" xlink:from="loc_us-gaap_CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalentsPeriodIncreaseDecreaseIncludingExchangeRateEffect_019c540a-9e2a-74cf-8d29-45a03fd3f465" xlink:to="loc_us-gaap_NetCashProvidedByUsedInInvestingActivities_019c540a-9e2a-7be1-9fed-8846e8f52b32" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NetCashProvidedByUsedInFinancingActivities_019c540a-9e2a-74a0-8000-c5e1b5504247" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_NetCashProvidedByUsedInFinancingActivities"/>
    <link:calculationArc order="3" weight="1.0" xlink:arcrole="https://xbrl.org/2023/arcrole/summation-item" xlink:from="loc_us-gaap_CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalentsPeriodIncreaseDecreaseIncludingExchangeRateEffect_019c540a-9e2a-74cf-8d29-45a03fd3f465" xlink:to="loc_us-gaap_NetCashProvidedByUsedInFinancingActivities_019c540a-9e2a-74a0-8000-c5e1b5504247" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NetCashProvidedByUsedInOperatingActivities_019c540a-9e2a-7f47-a34f-30ea8162be44" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_NetCashProvidedByUsedInOperatingActivities"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NetIncomeLoss_019c540a-9e2a-7d68-a1fa-918aa17bc489" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_NetIncomeLoss"/>
    <link:calculationArc order="1" weight="1.0" xlink:arcrole="https://xbrl.org/2023/arcrole/summation-item" xlink:from="loc_us-gaap_NetCashProvidedByUsedInOperatingActivities_019c540a-9e2a-7f47-a34f-30ea8162be44" xlink:to="loc_us-gaap_NetIncomeLoss_019c540a-9e2a-7d68-a1fa-918aa17bc489" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtSecuritiesAvailableForSaleRealizedGainLoss_019c540a-9e2a-716b-8890-d26138b83d3c" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DebtSecuritiesAvailableForSaleRealizedGainLoss"/>
    <link:calculationArc order="2" weight="-1.0" xlink:arcrole="https://xbrl.org/2023/arcrole/summation-item" xlink:from="loc_us-gaap_NetCashProvidedByUsedInOperatingActivities_019c540a-9e2a-7f47-a34f-30ea8162be44" xlink:to="loc_us-gaap_DebtSecuritiesAvailableForSaleRealizedGainLoss_019c540a-9e2a-716b-8890-d26138b83d3c" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DepreciationAmortizationAndAccretionNet_019c540a-9e2a-720b-8c81-19d72b106ad4" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DepreciationAmortizationAndAccretionNet"/>
    <link:calculationArc order="3" weight="1.0" xlink:arcrole="https://xbrl.org/2023/arcrole/summation-item" xlink:from="loc_us-gaap_NetCashProvidedByUsedInOperatingActivities_019c540a-9e2a-7f47-a34f-30ea8162be44" xlink:to="loc_us-gaap_DepreciationAmortizationAndAccretionNet_019c540a-9e2a-720b-8c81-19d72b106ad4" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AccretionAmortizationOfDiscountsAndPremiumsInvestments_019c540a-9e2a-7b96-883b-812de749f770" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_AccretionAmortizationOfDiscountsAndPremiumsInvestments"/>
    <link:calculationArc order="4" weight="-1.0" xlink:arcrole="https://xbrl.org/2023/arcrole/summation-item" xlink:from="loc_us-gaap_NetCashProvidedByUsedInOperatingActivities_019c540a-9e2a-7f47-a34f-30ea8162be44" xlink:to="loc_us-gaap_AccretionAmortizationOfDiscountsAndPremiumsInvestments_019c540a-9e2a-7b96-883b-812de749f770" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AmortizationOfFinancingCostsAndDiscounts_019c540a-9e2a-782f-90cb-962f076e524d" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_AmortizationOfFinancingCostsAndDiscounts"/>
    <link:calculationArc order="5" weight="1.0" xlink:arcrole="https://xbrl.org/2023/arcrole/summation-item" xlink:from="loc_us-gaap_NetCashProvidedByUsedInOperatingActivities_019c540a-9e2a-7f47-a34f-30ea8162be44" xlink:to="loc_us-gaap_AmortizationOfFinancingCostsAndDiscounts_019c540a-9e2a-782f-90cb-962f076e524d" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DeferredIncomeTaxesAndTaxCredits_019c540a-9e2a-794b-93cf-3be1641bd4f5" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DeferredIncomeTaxesAndTaxCredits"/>
    <link:calculationArc order="6" weight="1.0" xlink:arcrole="https://xbrl.org/2023/arcrole/summation-item" xlink:from="loc_us-gaap_NetCashProvidedByUsedInOperatingActivities_019c540a-9e2a-7f47-a34f-30ea8162be44" xlink:to="loc_us-gaap_DeferredIncomeTaxesAndTaxCredits_019c540a-9e2a-794b-93cf-3be1641bd4f5" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensation_019c540a-9e2a-74a6-943f-faae818c92cf" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ShareBasedCompensation"/>
    <link:calculationArc order="7" weight="1.0" xlink:arcrole="https://xbrl.org/2023/arcrole/summation-item" xlink:from="loc_us-gaap_NetCashProvidedByUsedInOperatingActivities_019c540a-9e2a-7f47-a34f-30ea8162be44" xlink:to="loc_us-gaap_ShareBasedCompensation_019c540a-9e2a-74a6-943f-faae818c92cf" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncreaseDecreaseInPremiumsReceivable_019c540a-9e2a-775f-995d-f97f93672a43" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_IncreaseDecreaseInPremiumsReceivable"/>
    <link:calculationArc order="8" weight="-1.0" xlink:arcrole="https://xbrl.org/2023/arcrole/summation-item" xlink:from="loc_us-gaap_NetCashProvidedByUsedInOperatingActivities_019c540a-9e2a-7f47-a34f-30ea8162be44" xlink:to="loc_us-gaap_IncreaseDecreaseInPremiumsReceivable_019c540a-9e2a-775f-995d-f97f93672a43" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncreaseDecreaseInAccruedInvestmentIncomeReceivable_019c540a-9e2a-7b73-8a26-cdbcbeee9315" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_IncreaseDecreaseInAccruedInvestmentIncomeReceivable"/>
    <link:calculationArc order="9" weight="-1.0" xlink:arcrole="https://xbrl.org/2023/arcrole/summation-item" xlink:from="loc_us-gaap_NetCashProvidedByUsedInOperatingActivities_019c540a-9e2a-7f47-a34f-30ea8162be44" xlink:to="loc_us-gaap_IncreaseDecreaseInAccruedInvestmentIncomeReceivable_019c540a-9e2a-7b73-8a26-cdbcbeee9315" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncreaseDecreaseInDeferredPolicyAcquisitionCosts_019c540a-9e2a-7c59-b40f-65370fe12ea2" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_IncreaseDecreaseInDeferredPolicyAcquisitionCosts"/>
    <link:calculationArc order="10" weight="-1.0" xlink:arcrole="https://xbrl.org/2023/arcrole/summation-item" xlink:from="loc_us-gaap_NetCashProvidedByUsedInOperatingActivities_019c540a-9e2a-7f47-a34f-30ea8162be44" xlink:to="loc_us-gaap_IncreaseDecreaseInDeferredPolicyAcquisitionCosts_019c540a-9e2a-7c59-b40f-65370fe12ea2" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncreaseDecreaseInReinsuranceRecoverable_019c540a-9e2a-73d4-9a55-9919bc70106b" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_IncreaseDecreaseInReinsuranceRecoverable"/>
    <link:calculationArc order="11" weight="-1.0" xlink:arcrole="https://xbrl.org/2023/arcrole/summation-item" xlink:from="loc_us-gaap_NetCashProvidedByUsedInOperatingActivities_019c540a-9e2a-7f47-a34f-30ea8162be44" xlink:to="loc_us-gaap_IncreaseDecreaseInReinsuranceRecoverable_019c540a-9e2a-73d4-9a55-9919bc70106b" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncreaseDecreaseInPrepaidDeferredExpenseAndOtherAssets_019c540a-9e2a-7eb4-b104-059571f6c363" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_IncreaseDecreaseInPrepaidDeferredExpenseAndOtherAssets"/>
    <link:calculationArc order="12" weight="-1.0" xlink:arcrole="https://xbrl.org/2023/arcrole/summation-item" xlink:from="loc_us-gaap_NetCashProvidedByUsedInOperatingActivities_019c540a-9e2a-7f47-a34f-30ea8162be44" xlink:to="loc_us-gaap_IncreaseDecreaseInPrepaidDeferredExpenseAndOtherAssets_019c540a-9e2a-7eb4-b104-059571f6c363" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncreaseDecreaseInUnearnedPremiums_019c540a-9e2a-7cd2-ad44-01ee0df79545" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_IncreaseDecreaseInUnearnedPremiums"/>
    <link:calculationArc order="13" weight="1.0" xlink:arcrole="https://xbrl.org/2023/arcrole/summation-item" xlink:from="loc_us-gaap_NetCashProvidedByUsedInOperatingActivities_019c540a-9e2a-7f47-a34f-30ea8162be44" xlink:to="loc_us-gaap_IncreaseDecreaseInUnearnedPremiums_019c540a-9e2a-7cd2-ad44-01ee0df79545" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncreaseDecreaseInLiabilityForClaimsAndClaimsAdjustmentExpenseReserve_019c540a-9e2a-7670-881e-c63735415ca1" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_IncreaseDecreaseInLiabilityForClaimsAndClaimsAdjustmentExpenseReserve"/>
    <link:calculationArc order="14" weight="1.0" xlink:arcrole="https://xbrl.org/2023/arcrole/summation-item" xlink:from="loc_us-gaap_NetCashProvidedByUsedInOperatingActivities_019c540a-9e2a-7f47-a34f-30ea8162be44" xlink:to="loc_us-gaap_IncreaseDecreaseInLiabilityForClaimsAndClaimsAdjustmentExpenseReserve_019c540a-9e2a-7670-881e-c63735415ca1" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_nmih_IncreaseDecreaseinReinsuranceAssetsandLiabilities_019c540a-9e2a-7ab6-8b28-936d140f9859" xlink:href="nmih-20260331.xsd#nmih_IncreaseDecreaseinReinsuranceAssetsandLiabilities"/>
    <link:calculationArc order="15" weight="-1.0" xlink:arcrole="https://xbrl.org/2023/arcrole/summation-item" xlink:from="loc_us-gaap_NetCashProvidedByUsedInOperatingActivities_019c540a-9e2a-7f47-a34f-30ea8162be44" xlink:to="loc_nmih_IncreaseDecreaseinReinsuranceAssetsandLiabilities_019c540a-9e2a-7ab6-8b28-936d140f9859" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncreaseDecreaseInAccountsPayableAndAccruedLiabilities_019c540a-9e2a-73a8-80ac-578290f8f65b" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_IncreaseDecreaseInAccountsPayableAndAccruedLiabilities"/>
    <link:calculationArc order="16" weight="1.0" xlink:arcrole="https://xbrl.org/2023/arcrole/summation-item" xlink:from="loc_us-gaap_NetCashProvidedByUsedInOperatingActivities_019c540a-9e2a-7f47-a34f-30ea8162be44" xlink:to="loc_us-gaap_IncreaseDecreaseInAccountsPayableAndAccruedLiabilities_019c540a-9e2a-73a8-80ac-578290f8f65b" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NetCashProvidedByUsedInFinancingActivities_019c540a-9e2a-7595-b73d-c4483b1276a2" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_NetCashProvidedByUsedInFinancingActivities"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ProceedsFromIssuanceOfSharesUnderIncentiveAndShareBasedCompensationPlansIncludingStockOptions_019c540a-9e2a-797b-b47b-80db733b1fbd" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ProceedsFromIssuanceOfSharesUnderIncentiveAndShareBasedCompensationPlansIncludingStockOptions"/>
    <link:calculationArc order="1" weight="1.0" xlink:arcrole="https://xbrl.org/2023/arcrole/summation-item" xlink:from="loc_us-gaap_NetCashProvidedByUsedInFinancingActivities_019c540a-9e2a-7595-b73d-c4483b1276a2" xlink:to="loc_us-gaap_ProceedsFromIssuanceOfSharesUnderIncentiveAndShareBasedCompensationPlansIncludingStockOptions_019c540a-9e2a-797b-b47b-80db733b1fbd" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PaymentsRelatedToTaxWithholdingForShareBasedCompensation_019c540a-9e2a-79c2-ae79-d04ff58962a7" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_PaymentsRelatedToTaxWithholdingForShareBasedCompensation"/>
    <link:calculationArc order="2" weight="-1.0" xlink:arcrole="https://xbrl.org/2023/arcrole/summation-item" xlink:from="loc_us-gaap_NetCashProvidedByUsedInFinancingActivities_019c540a-9e2a-7595-b73d-c4483b1276a2" xlink:to="loc_us-gaap_PaymentsRelatedToTaxWithholdingForShareBasedCompensation_019c540a-9e2a-79c2-ae79-d04ff58962a7" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PaymentsForRepurchaseOfCommonStock_019c540a-9e2a-723d-aefa-7dbc3f7a3c16" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_PaymentsForRepurchaseOfCommonStock"/>
    <link:calculationArc order="3" weight="-1.0" xlink:arcrole="https://xbrl.org/2023/arcrole/summation-item" xlink:from="loc_us-gaap_NetCashProvidedByUsedInFinancingActivities_019c540a-9e2a-7595-b73d-c4483b1276a2" xlink:to="loc_us-gaap_PaymentsForRepurchaseOfCommonStock_019c540a-9e2a-723d-aefa-7dbc3f7a3c16" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NetCashProvidedByUsedInInvestingActivities_019c540a-9e2a-7494-a8bf-7f401b000dd3" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_NetCashProvidedByUsedInInvestingActivities"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PaymentsToAcquireAvailableForSaleSecuritiesDebt_019c540a-9e2a-7e1d-a57e-e96664bffc97" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_PaymentsToAcquireAvailableForSaleSecuritiesDebt"/>
    <link:calculationArc order="1" weight="-1.0" xlink:arcrole="https://xbrl.org/2023/arcrole/summation-item" xlink:from="loc_us-gaap_NetCashProvidedByUsedInInvestingActivities_019c540a-9e2a-7494-a8bf-7f401b000dd3" xlink:to="loc_us-gaap_PaymentsToAcquireAvailableForSaleSecuritiesDebt_019c540a-9e2a-7e1d-a57e-e96664bffc97" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ProceedsFromSaleOfShortTermInvestments_019c540a-9e2a-7e50-8a12-94b612fb56ba" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ProceedsFromSaleOfShortTermInvestments"/>
    <link:calculationArc order="2" weight="1.0" xlink:arcrole="https://xbrl.org/2023/arcrole/summation-item" xlink:from="loc_us-gaap_NetCashProvidedByUsedInInvestingActivities_019c540a-9e2a-7494-a8bf-7f401b000dd3" xlink:to="loc_us-gaap_ProceedsFromSaleOfShortTermInvestments_019c540a-9e2a-7e50-8a12-94b612fb56ba" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ProceedsFromMaturitiesPrepaymentsAndCallsOfAvailableForSaleSecurities_019c540a-9e2a-7ed9-bce6-041d0d9e528d" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ProceedsFromMaturitiesPrepaymentsAndCallsOfAvailableForSaleSecurities"/>
    <link:calculationArc order="3" weight="1.0" xlink:arcrole="https://xbrl.org/2023/arcrole/summation-item" xlink:from="loc_us-gaap_NetCashProvidedByUsedInInvestingActivities_019c540a-9e2a-7494-a8bf-7f401b000dd3" xlink:to="loc_us-gaap_ProceedsFromMaturitiesPrepaymentsAndCallsOfAvailableForSaleSecurities_019c540a-9e2a-7ed9-bce6-041d0d9e528d" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ProceedsFromSaleOfAvailableForSaleSecuritiesDebt_019c540a-9e2a-76a7-82c1-b3321e6f0cf0" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ProceedsFromSaleOfAvailableForSaleSecuritiesDebt"/>
    <link:calculationArc order="4" weight="1.0" xlink:arcrole="https://xbrl.org/2023/arcrole/summation-item" xlink:from="loc_us-gaap_NetCashProvidedByUsedInInvestingActivities_019c540a-9e2a-7494-a8bf-7f401b000dd3" xlink:to="loc_us-gaap_ProceedsFromSaleOfAvailableForSaleSecuritiesDebt_019c540a-9e2a-76a7-82c1-b3321e6f0cf0" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PaymentsToAcquirePropertyPlantAndEquipment_019c540a-9e2a-7cf9-beb8-155795489baa" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_PaymentsToAcquirePropertyPlantAndEquipment"/>
    <link:calculationArc order="5" weight="-1.0" xlink:arcrole="https://xbrl.org/2023/arcrole/summation-item" xlink:from="loc_us-gaap_NetCashProvidedByUsedInInvestingActivities_019c540a-9e2a-7494-a8bf-7f401b000dd3" xlink:to="loc_us-gaap_PaymentsToAcquirePropertyPlantAndEquipment_019c540a-9e2a-7cf9-beb8-155795489baa" xlink:type="arc"/>
  </link:calculationLink>
  <link:roleRef roleURI="http://www.nationalmi.com/role/InvestmentsScheduleofFairValuesandGrossUnrealizedGainsandLossesDetails" xlink:type="simple" xlink:href="nmih-20260331.xsd#InvestmentsScheduleofFairValuesandGrossUnrealizedGainsandLossesDetails"/>
  <link:calculationLink xlink:role="http://www.nationalmi.com/role/InvestmentsScheduleofFairValuesandGrossUnrealizedGainsandLossesDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AvailableForSaleDebtSecuritiesAmortizedCostBasis_019c540a-9e2a-7240-a993-18fcb43c39c2" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_AvailableForSaleDebtSecuritiesAmortizedCostBasis"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AvailableForSaleDebtSecuritiesAccumulatedGrossUnrealizedGainBeforeTax_019c540a-9e2a-7ab5-99e8-b71e0097dcf8" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_AvailableForSaleDebtSecuritiesAccumulatedGrossUnrealizedGainBeforeTax"/>
    <link:calculationArc order="1" weight="-1.0" xlink:arcrole="https://xbrl.org/2023/arcrole/summation-item" xlink:from="loc_us-gaap_AvailableForSaleDebtSecuritiesAmortizedCostBasis_019c540a-9e2a-7240-a993-18fcb43c39c2" xlink:to="loc_us-gaap_AvailableForSaleDebtSecuritiesAccumulatedGrossUnrealizedGainBeforeTax_019c540a-9e2a-7ab5-99e8-b71e0097dcf8" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AvailableForSaleDebtSecuritiesAccumulatedGrossUnrealizedLossBeforeTax_019c540a-9e2a-7f80-ab9b-99440c6cf920" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_AvailableForSaleDebtSecuritiesAccumulatedGrossUnrealizedLossBeforeTax"/>
    <link:calculationArc order="2" weight="1.0" xlink:arcrole="https://xbrl.org/2023/arcrole/summation-item" xlink:from="loc_us-gaap_AvailableForSaleDebtSecuritiesAmortizedCostBasis_019c540a-9e2a-7240-a993-18fcb43c39c2" xlink:to="loc_us-gaap_AvailableForSaleDebtSecuritiesAccumulatedGrossUnrealizedLossBeforeTax_019c540a-9e2a-7f80-ab9b-99440c6cf920" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AvailableForSaleSecuritiesDebtSecurities_019c540a-9e2a-7489-9076-b38fc13a5423" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_AvailableForSaleSecuritiesDebtSecurities"/>
    <link:calculationArc order="3" weight="1.0" xlink:arcrole="https://xbrl.org/2023/arcrole/summation-item" xlink:from="loc_us-gaap_AvailableForSaleDebtSecuritiesAmortizedCostBasis_019c540a-9e2a-7240-a993-18fcb43c39c2" xlink:to="loc_us-gaap_AvailableForSaleSecuritiesDebtSecurities_019c540a-9e2a-7489-9076-b38fc13a5423" xlink:type="arc"/>
  </link:calculationLink>
  <link:roleRef roleURI="http://www.nationalmi.com/role/InvestmentsScheduleofInvestmentsbyMaturityDetails" xlink:type="simple" xlink:href="nmih-20260331.xsd#InvestmentsScheduleofInvestmentsbyMaturityDetails"/>
  <link:calculationLink xlink:role="http://www.nationalmi.com/role/InvestmentsScheduleofInvestmentsbyMaturityDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AvailableForSaleSecuritiesDebtSecurities_019c540a-9e2a-7696-8572-fda80c215600" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_AvailableForSaleSecuritiesDebtSecurities"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AvailableForSaleSecuritiesDebtMaturitiesNextRollingTwelveMonthsFairValue_019c540a-9e2a-7973-924c-7f6a86b15c4f" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_AvailableForSaleSecuritiesDebtMaturitiesNextRollingTwelveMonthsFairValue"/>
    <link:calculationArc order="1" weight="1.0" xlink:arcrole="https://xbrl.org/2023/arcrole/summation-item" xlink:from="loc_us-gaap_AvailableForSaleSecuritiesDebtSecurities_019c540a-9e2a-7696-8572-fda80c215600" xlink:to="loc_us-gaap_AvailableForSaleSecuritiesDebtMaturitiesNextRollingTwelveMonthsFairValue_019c540a-9e2a-7973-924c-7f6a86b15c4f" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AvailableForSaleSecuritiesDebtMaturitiesRollingYearTwoThroughFiveFairValue_019c540a-9e2a-7acb-af87-bbe883209150" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_AvailableForSaleSecuritiesDebtMaturitiesRollingYearTwoThroughFiveFairValue"/>
    <link:calculationArc order="2" weight="1.0" xlink:arcrole="https://xbrl.org/2023/arcrole/summation-item" xlink:from="loc_us-gaap_AvailableForSaleSecuritiesDebtSecurities_019c540a-9e2a-7696-8572-fda80c215600" xlink:to="loc_us-gaap_AvailableForSaleSecuritiesDebtMaturitiesRollingYearTwoThroughFiveFairValue_019c540a-9e2a-7acb-af87-bbe883209150" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AvailableForSaleSecuritiesDebtMaturitiesRollingYearSixThroughTenFairValue_019c540a-9e2a-7be0-895c-db2d389508ed" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_AvailableForSaleSecuritiesDebtMaturitiesRollingYearSixThroughTenFairValue"/>
    <link:calculationArc order="3" weight="1.0" xlink:arcrole="https://xbrl.org/2023/arcrole/summation-item" xlink:from="loc_us-gaap_AvailableForSaleSecuritiesDebtSecurities_019c540a-9e2a-7696-8572-fda80c215600" xlink:to="loc_us-gaap_AvailableForSaleSecuritiesDebtMaturitiesRollingYearSixThroughTenFairValue_019c540a-9e2a-7be0-895c-db2d389508ed" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AvailableForSaleSecuritiesDebtMaturitiesRollingAfterYearTenFairValue_019c540a-9e2a-77b0-a333-54667889f6fe" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_AvailableForSaleSecuritiesDebtMaturitiesRollingAfterYearTenFairValue"/>
    <link:calculationArc order="4" weight="1.0" xlink:arcrole="https://xbrl.org/2023/arcrole/summation-item" xlink:from="loc_us-gaap_AvailableForSaleSecuritiesDebtSecurities_019c540a-9e2a-7696-8572-fda80c215600" xlink:to="loc_us-gaap_AvailableForSaleSecuritiesDebtMaturitiesRollingAfterYearTenFairValue_019c540a-9e2a-77b0-a333-54667889f6fe" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AvailableForSaleSecuritiesDebtMaturitiesWithoutSingleMaturityDateFairValue_019c540a-9e2a-799b-b98f-183322105ec7" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_AvailableForSaleSecuritiesDebtMaturitiesWithoutSingleMaturityDateFairValue"/>
    <link:calculationArc order="5" weight="1.0" xlink:arcrole="https://xbrl.org/2023/arcrole/summation-item" xlink:from="loc_us-gaap_AvailableForSaleSecuritiesDebtSecurities_019c540a-9e2a-7696-8572-fda80c215600" xlink:to="loc_us-gaap_AvailableForSaleSecuritiesDebtMaturitiesWithoutSingleMaturityDateFairValue_019c540a-9e2a-799b-b98f-183322105ec7" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AvailableForSaleDebtSecuritiesAmortizedCostBasis_019c540a-9e2a-7784-a5cd-b67f2054c3a4" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_AvailableForSaleDebtSecuritiesAmortizedCostBasis"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AvailableForSaleSecuritiesDebtMaturitiesNextRollingTwelveMonthsAmortizedCostBasis_019c540a-9e2a-7aa2-8cd9-8068976ae001" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_AvailableForSaleSecuritiesDebtMaturitiesNextRollingTwelveMonthsAmortizedCostBasis"/>
    <link:calculationArc order="1" weight="1.0" xlink:arcrole="https://xbrl.org/2023/arcrole/summation-item" xlink:from="loc_us-gaap_AvailableForSaleDebtSecuritiesAmortizedCostBasis_019c540a-9e2a-7784-a5cd-b67f2054c3a4" xlink:to="loc_us-gaap_AvailableForSaleSecuritiesDebtMaturitiesNextRollingTwelveMonthsAmortizedCostBasis_019c540a-9e2a-7aa2-8cd9-8068976ae001" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AvailableForSaleSecuritiesDebtMaturitiesRollingYearTwoThroughFiveAmortizedCostBasis_019c540a-9e2a-756d-9115-743d6846de3f" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_AvailableForSaleSecuritiesDebtMaturitiesRollingYearTwoThroughFiveAmortizedCostBasis"/>
    <link:calculationArc order="2" weight="1.0" xlink:arcrole="https://xbrl.org/2023/arcrole/summation-item" xlink:from="loc_us-gaap_AvailableForSaleDebtSecuritiesAmortizedCostBasis_019c540a-9e2a-7784-a5cd-b67f2054c3a4" xlink:to="loc_us-gaap_AvailableForSaleSecuritiesDebtMaturitiesRollingYearTwoThroughFiveAmortizedCostBasis_019c540a-9e2a-756d-9115-743d6846de3f" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AvailableForSaleSecuritiesDebtMaturitiesRollingYearSixThroughTenAmortizedCostBasis_019c540a-9e2a-7033-81fe-dd46a129bf31" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_AvailableForSaleSecuritiesDebtMaturitiesRollingYearSixThroughTenAmortizedCostBasis"/>
    <link:calculationArc order="3" weight="1.0" xlink:arcrole="https://xbrl.org/2023/arcrole/summation-item" xlink:from="loc_us-gaap_AvailableForSaleDebtSecuritiesAmortizedCostBasis_019c540a-9e2a-7784-a5cd-b67f2054c3a4" xlink:to="loc_us-gaap_AvailableForSaleSecuritiesDebtMaturitiesRollingYearSixThroughTenAmortizedCostBasis_019c540a-9e2a-7033-81fe-dd46a129bf31" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AvailableForSaleSecuritiesDebtMaturitiesRollingAfterYearTenAmortizedCostBasis_019c540a-9e2a-7a7a-abf7-c61d6c8c28fb" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_AvailableForSaleSecuritiesDebtMaturitiesRollingAfterYearTenAmortizedCostBasis"/>
    <link:calculationArc order="4" weight="1.0" xlink:arcrole="https://xbrl.org/2023/arcrole/summation-item" xlink:from="loc_us-gaap_AvailableForSaleDebtSecuritiesAmortizedCostBasis_019c540a-9e2a-7784-a5cd-b67f2054c3a4" xlink:to="loc_us-gaap_AvailableForSaleSecuritiesDebtMaturitiesRollingAfterYearTenAmortizedCostBasis_019c540a-9e2a-7a7a-abf7-c61d6c8c28fb" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AvailableForSaleSecuritiesDebtMaturitiesWithoutSingleMaturityDateAmortizedCost_019c540a-9e2a-769b-af9b-2e45b1e0de59" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_AvailableForSaleSecuritiesDebtMaturitiesWithoutSingleMaturityDateAmortizedCost"/>
    <link:calculationArc order="5" weight="1.0" xlink:arcrole="https://xbrl.org/2023/arcrole/summation-item" xlink:from="loc_us-gaap_AvailableForSaleDebtSecuritiesAmortizedCostBasis_019c540a-9e2a-7784-a5cd-b67f2054c3a4" xlink:to="loc_us-gaap_AvailableForSaleSecuritiesDebtMaturitiesWithoutSingleMaturityDateAmortizedCost_019c540a-9e2a-769b-af9b-2e45b1e0de59" xlink:type="arc"/>
  </link:calculationLink>
  <link:roleRef roleURI="http://www.nationalmi.com/role/InvestmentsScheduleofAgingofUnrealizedLossesDetails" xlink:type="simple" xlink:href="nmih-20260331.xsd#InvestmentsScheduleofAgingofUnrealizedLossesDetails"/>
  <link:calculationLink xlink:role="http://www.nationalmi.com/role/InvestmentsScheduleofAgingofUnrealizedLossesDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtSecuritiesAvailableForSaleUnrealizedLossPositionAccumulatedLoss_019c540a-9e2a-762f-b1d5-a994fbc88bce" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DebtSecuritiesAvailableForSaleUnrealizedLossPositionAccumulatedLoss"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtSecuritiesAvailableForSaleContinuousUnrealizedLossPositionLessThan12MonthsAccumulatedLoss_019c540a-9e2a-7ea1-8b29-d3a3cff778b2" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DebtSecuritiesAvailableForSaleContinuousUnrealizedLossPositionLessThan12MonthsAccumulatedLoss"/>
    <link:calculationArc order="1" weight="1.0" xlink:arcrole="https://xbrl.org/2023/arcrole/summation-item" xlink:from="loc_us-gaap_DebtSecuritiesAvailableForSaleUnrealizedLossPositionAccumulatedLoss_019c540a-9e2a-762f-b1d5-a994fbc88bce" xlink:to="loc_us-gaap_DebtSecuritiesAvailableForSaleContinuousUnrealizedLossPositionLessThan12MonthsAccumulatedLoss_019c540a-9e2a-7ea1-8b29-d3a3cff778b2" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtSecuritiesAvailableForSaleContinuousUnrealizedLossPosition12MonthsOrLongerAccumulatedLoss_019c540a-9e2a-7e85-8776-1d7988d5cf26" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DebtSecuritiesAvailableForSaleContinuousUnrealizedLossPosition12MonthsOrLongerAccumulatedLoss"/>
    <link:calculationArc order="2" weight="1.0" xlink:arcrole="https://xbrl.org/2023/arcrole/summation-item" xlink:from="loc_us-gaap_DebtSecuritiesAvailableForSaleUnrealizedLossPositionAccumulatedLoss_019c540a-9e2a-762f-b1d5-a994fbc88bce" xlink:to="loc_us-gaap_DebtSecuritiesAvailableForSaleContinuousUnrealizedLossPosition12MonthsOrLongerAccumulatedLoss_019c540a-9e2a-7e85-8776-1d7988d5cf26" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtSecuritiesAvailableForSaleUnrealizedLossPosition_019c540a-9e2a-7eed-ad33-60ba523e7616" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DebtSecuritiesAvailableForSaleUnrealizedLossPosition"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtSecuritiesAvailableForSaleContinuousUnrealizedLossPositionLessThan12Months_019c540a-9e2a-74b5-b3e6-2d23acfe8d48" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DebtSecuritiesAvailableForSaleContinuousUnrealizedLossPositionLessThan12Months"/>
    <link:calculationArc order="1" weight="1.0" xlink:arcrole="https://xbrl.org/2023/arcrole/summation-item" xlink:from="loc_us-gaap_DebtSecuritiesAvailableForSaleUnrealizedLossPosition_019c540a-9e2a-7eed-ad33-60ba523e7616" xlink:to="loc_us-gaap_DebtSecuritiesAvailableForSaleContinuousUnrealizedLossPositionLessThan12Months_019c540a-9e2a-74b5-b3e6-2d23acfe8d48" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtSecuritiesAvailableForSaleContinuousUnrealizedLossPosition12MonthsOrLonger_019c540a-9e2a-78dc-ab8a-b78336d613d3" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DebtSecuritiesAvailableForSaleContinuousUnrealizedLossPosition12MonthsOrLonger"/>
    <link:calculationArc order="2" weight="1.0" xlink:arcrole="https://xbrl.org/2023/arcrole/summation-item" xlink:from="loc_us-gaap_DebtSecuritiesAvailableForSaleUnrealizedLossPosition_019c540a-9e2a-7eed-ad33-60ba523e7616" xlink:to="loc_us-gaap_DebtSecuritiesAvailableForSaleContinuousUnrealizedLossPosition12MonthsOrLonger_019c540a-9e2a-78dc-ab8a-b78336d613d3" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtSecuritiesAvailableForSaleUnrealizedLossPositionNumberOfPositions_019c540a-9e2a-780d-ac35-c28cca13084d" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DebtSecuritiesAvailableForSaleUnrealizedLossPositionNumberOfPositions"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtSecuritiesAvailableForSaleContinuousUnrealizedLossPositionLessThan12MonthsNumberOfPositions_019c540a-9e2a-73b2-ba2d-dedead28024e" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DebtSecuritiesAvailableForSaleContinuousUnrealizedLossPositionLessThan12MonthsNumberOfPositions"/>
    <link:calculationArc order="1" weight="1.0" xlink:arcrole="https://xbrl.org/2023/arcrole/summation-item" xlink:from="loc_us-gaap_DebtSecuritiesAvailableForSaleUnrealizedLossPositionNumberOfPositions_019c540a-9e2a-780d-ac35-c28cca13084d" xlink:to="loc_us-gaap_DebtSecuritiesAvailableForSaleContinuousUnrealizedLossPositionLessThan12MonthsNumberOfPositions_019c540a-9e2a-73b2-ba2d-dedead28024e" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtSecuritiesAvailableForSaleContinuousUnrealizedLossPosition12MonthsOrLongerNumberOfPositions_019c540a-9e2a-7937-b65e-46768b8b4344" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DebtSecuritiesAvailableForSaleContinuousUnrealizedLossPosition12MonthsOrLongerNumberOfPositions"/>
    <link:calculationArc order="2" weight="1.0" xlink:arcrole="https://xbrl.org/2023/arcrole/summation-item" xlink:from="loc_us-gaap_DebtSecuritiesAvailableForSaleUnrealizedLossPositionNumberOfPositions_019c540a-9e2a-780d-ac35-c28cca13084d" xlink:to="loc_us-gaap_DebtSecuritiesAvailableForSaleContinuousUnrealizedLossPosition12MonthsOrLongerNumberOfPositions_019c540a-9e2a-7937-b65e-46768b8b4344" xlink:type="arc"/>
  </link:calculationLink>
  <link:roleRef roleURI="http://www.nationalmi.com/role/InvestmentsScheduleofNetInvestmentIncomeDetails" xlink:type="simple" xlink:href="nmih-20260331.xsd#InvestmentsScheduleofNetInvestmentIncomeDetails"/>
  <link:calculationLink xlink:role="http://www.nationalmi.com/role/InvestmentsScheduleofNetInvestmentIncomeDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_InvestmentIncomeNet_019c540a-9e2a-7e35-9c03-bf9404764947" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_InvestmentIncomeNet"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_InvestmentIncomeInterestAndDividend_019c540a-9e2a-721b-9f29-eeed3ee09c9e" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_InvestmentIncomeInterestAndDividend"/>
    <link:calculationArc order="1" weight="1.0" xlink:arcrole="https://xbrl.org/2023/arcrole/summation-item" xlink:from="loc_us-gaap_InvestmentIncomeNet_019c540a-9e2a-7e35-9c03-bf9404764947" xlink:to="loc_us-gaap_InvestmentIncomeInterestAndDividend_019c540a-9e2a-721b-9f29-eeed3ee09c9e" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_InvestmentIncomeInvestmentExpense_019c540a-9e2a-76f1-85bc-588ec3e6a178" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_InvestmentIncomeInvestmentExpense"/>
    <link:calculationArc order="2" weight="-1.0" xlink:arcrole="https://xbrl.org/2023/arcrole/summation-item" xlink:from="loc_us-gaap_InvestmentIncomeNet_019c540a-9e2a-7e35-9c03-bf9404764947" xlink:to="loc_us-gaap_InvestmentIncomeInvestmentExpense_019c540a-9e2a-76f1-85bc-588ec3e6a178" xlink:type="arc"/>
  </link:calculationLink>
  <link:roleRef roleURI="http://www.nationalmi.com/role/InvestmentsScheduleofNetRealizedInvestmentGainsLossesDetails" xlink:type="simple" xlink:href="nmih-20260331.xsd#InvestmentsScheduleofNetRealizedInvestmentGainsLossesDetails"/>
  <link:calculationLink xlink:role="http://www.nationalmi.com/role/InvestmentsScheduleofNetRealizedInvestmentGainsLossesDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtSecuritiesAvailableForSaleRealizedGainLoss_019c540a-9e2a-713a-8e83-736a2874a9f6" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DebtSecuritiesAvailableForSaleRealizedGainLoss"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtSecuritiesAvailableForSaleRealizedGain_019c540a-9e2a-778b-a284-57a42f44e7c0" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DebtSecuritiesAvailableForSaleRealizedGain"/>
    <link:calculationArc order="1" weight="1.0" xlink:arcrole="https://xbrl.org/2023/arcrole/summation-item" xlink:from="loc_us-gaap_DebtSecuritiesAvailableForSaleRealizedGainLoss_019c540a-9e2a-713a-8e83-736a2874a9f6" xlink:to="loc_us-gaap_DebtSecuritiesAvailableForSaleRealizedGain_019c540a-9e2a-778b-a284-57a42f44e7c0" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtSecuritiesAvailableForSaleRealizedLoss_019c540a-9e2a-7fa6-bb17-38006513b571" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DebtSecuritiesAvailableForSaleRealizedLoss"/>
    <link:calculationArc order="2" weight="-1.0" xlink:arcrole="https://xbrl.org/2023/arcrole/summation-item" xlink:from="loc_us-gaap_DebtSecuritiesAvailableForSaleRealizedGainLoss_019c540a-9e2a-713a-8e83-736a2874a9f6" xlink:to="loc_us-gaap_DebtSecuritiesAvailableForSaleRealizedLoss_019c540a-9e2a-7fa6-bb17-38006513b571" xlink:type="arc"/>
  </link:calculationLink>
  <link:roleRef roleURI="http://www.nationalmi.com/role/FairValueofFinancialInstrumentsScheduleofFairValueMeasurementsofFinancialInstrumentsDetails" xlink:type="simple" xlink:href="nmih-20260331.xsd#FairValueofFinancialInstrumentsScheduleofFairValueMeasurementsofFinancialInstrumentsDetails"/>
  <link:calculationLink xlink:role="http://www.nationalmi.com/role/FairValueofFinancialInstrumentsScheduleofFairValueMeasurementsofFinancialInstrumentsDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AssetsFairValueDisclosure_019c540a-9e2a-7f1a-99e6-8b4272b9ed6b" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_AssetsFairValueDisclosure"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AvailableForSaleSecuritiesDebtSecurities_019c540a-9e2a-7eeb-b79d-493cce00a215" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_AvailableForSaleSecuritiesDebtSecurities"/>
    <link:calculationArc order="1" weight="1.0" xlink:arcrole="https://xbrl.org/2023/arcrole/summation-item" xlink:from="loc_us-gaap_AssetsFairValueDisclosure_019c540a-9e2a-7f1a-99e6-8b4272b9ed6b" xlink:to="loc_us-gaap_AvailableForSaleSecuritiesDebtSecurities_019c540a-9e2a-7eeb-b79d-493cce00a215" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CashAndCashEquivalentsFairValueDisclosure_019c540a-9e2a-7e42-b34f-c8bd5d9e1696" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_CashAndCashEquivalentsFairValueDisclosure"/>
    <link:calculationArc order="2" weight="1.0" xlink:arcrole="https://xbrl.org/2023/arcrole/summation-item" xlink:from="loc_us-gaap_AssetsFairValueDisclosure_019c540a-9e2a-7f1a-99e6-8b4272b9ed6b" xlink:to="loc_us-gaap_CashAndCashEquivalentsFairValueDisclosure_019c540a-9e2a-7e42-b34f-c8bd5d9e1696" xlink:type="arc"/>
  </link:calculationLink>
  <link:roleRef roleURI="http://www.nationalmi.com/role/ReinsuranceScheduleofEffectofReinsuranceAgreementsonPremiumsWrittenandEarnedDetails" xlink:type="simple" xlink:href="nmih-20260331.xsd#ReinsuranceScheduleofEffectofReinsuranceAgreementsonPremiumsWrittenandEarnedDetails"/>
  <link:calculationLink xlink:role="http://www.nationalmi.com/role/ReinsuranceScheduleofEffectofReinsuranceAgreementsonPremiumsWrittenandEarnedDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PremiumsWrittenNet_019c540a-9e2a-7733-9403-cf5d7460136a" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_PremiumsWrittenNet"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DirectPremiumsWritten_019c540a-9e2a-7420-9740-1f597be6950f" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DirectPremiumsWritten"/>
    <link:calculationArc order="1" weight="1.0" xlink:arcrole="https://xbrl.org/2023/arcrole/summation-item" xlink:from="loc_us-gaap_PremiumsWrittenNet_019c540a-9e2a-7733-9403-cf5d7460136a" xlink:to="loc_us-gaap_DirectPremiumsWritten_019c540a-9e2a-7420-9740-1f597be6950f" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CededPremiumsWritten_019c540a-9e2a-7ca6-bcdb-c3fe26d567ac" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_CededPremiumsWritten"/>
    <link:calculationArc order="2" weight="-1.0" xlink:arcrole="https://xbrl.org/2023/arcrole/summation-item" xlink:from="loc_us-gaap_PremiumsWrittenNet_019c540a-9e2a-7733-9403-cf5d7460136a" xlink:to="loc_us-gaap_CededPremiumsWritten_019c540a-9e2a-7ca6-bcdb-c3fe26d567ac" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PremiumsEarnedNet_019c540a-9e2a-720b-9321-e88d8a5856c9" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_PremiumsEarnedNet"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DirectPremiumsEarned_019c540a-9e2a-7c28-873b-b08324941ec5" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DirectPremiumsEarned"/>
    <link:calculationArc order="1" weight="1.0" xlink:arcrole="https://xbrl.org/2023/arcrole/summation-item" xlink:from="loc_us-gaap_PremiumsEarnedNet_019c540a-9e2a-720b-9321-e88d8a5856c9" xlink:to="loc_us-gaap_DirectPremiumsEarned_019c540a-9e2a-7c28-873b-b08324941ec5" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CededPremiumsEarned_019c540a-9e2a-7a03-88c9-0fd67548624b" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_CededPremiumsEarned"/>
    <link:calculationArc order="2" weight="-1.0" xlink:arcrole="https://xbrl.org/2023/arcrole/summation-item" xlink:from="loc_us-gaap_PremiumsEarnedNet_019c540a-9e2a-720b-9321-e88d8a5856c9" xlink:to="loc_us-gaap_CededPremiumsEarned_019c540a-9e2a-7a03-88c9-0fd67548624b" xlink:type="arc"/>
  </link:calculationLink>
  <link:roleRef roleURI="http://www.nationalmi.com/role/ReservesforInsuranceClaimsandClaimExpensesScheduleofReconciliationofLiabilityforInsuranceClaimsandClaimExpensesDetails" xlink:type="simple" xlink:href="nmih-20260331.xsd#ReservesforInsuranceClaimsandClaimExpensesScheduleofReconciliationofLiabilityforInsuranceClaimsandClaimExpensesDetails"/>
  <link:calculationLink xlink:role="http://www.nationalmi.com/role/ReservesforInsuranceClaimsandClaimExpensesScheduleofReconciliationofLiabilityforInsuranceClaimsandClaimExpensesDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LiabilityForUnpaidClaimsAndClaimsAdjustmentExpenseNet_019c540a-9e2a-7073-900f-a15083306956" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_LiabilityForUnpaidClaimsAndClaimsAdjustmentExpenseNet"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LiabilityForClaimsAndClaimsAdjustmentExpense_019c540a-9e2a-7cb4-8ed8-aa4151ff1876" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_LiabilityForClaimsAndClaimsAdjustmentExpense"/>
    <link:calculationArc order="1" weight="1.0" xlink:arcrole="https://xbrl.org/2023/arcrole/summation-item" xlink:from="loc_us-gaap_LiabilityForUnpaidClaimsAndClaimsAdjustmentExpenseNet_019c540a-9e2a-7073-900f-a15083306956" xlink:to="loc_us-gaap_LiabilityForClaimsAndClaimsAdjustmentExpense_019c540a-9e2a-7cb4-8ed8-aa4151ff1876" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ReinsuranceRecoverablesOnPaidAndUnpaidLosses_019c540a-9e2a-7d8b-9787-24f713cc997d" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ReinsuranceRecoverablesOnPaidAndUnpaidLosses"/>
    <link:calculationArc order="2" weight="-1.0" xlink:arcrole="https://xbrl.org/2023/arcrole/summation-item" xlink:from="loc_us-gaap_LiabilityForUnpaidClaimsAndClaimsAdjustmentExpenseNet_019c540a-9e2a-7073-900f-a15083306956" xlink:to="loc_us-gaap_ReinsuranceRecoverablesOnPaidAndUnpaidLosses_019c540a-9e2a-7d8b-9787-24f713cc997d" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LiabilityForUnpaidClaimsAndClaimsAdjustmentExpenseIncurredClaims1_019c540a-9e2a-7b93-839d-eb4a15f610a8" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_LiabilityForUnpaidClaimsAndClaimsAdjustmentExpenseIncurredClaims1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SupplementalInformationForPropertyCasualtyInsuranceUnderwritersCurrentYearClaimsAndClaimsAdjustmentExpense_019c540a-9e2a-733d-95b7-b63bb5ab8413" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_SupplementalInformationForPropertyCasualtyInsuranceUnderwritersCurrentYearClaimsAndClaimsAdjustmentExpense"/>
    <link:calculationArc order="1" weight="1.0" xlink:arcrole="https://xbrl.org/2023/arcrole/summation-item" xlink:from="loc_us-gaap_LiabilityForUnpaidClaimsAndClaimsAdjustmentExpenseIncurredClaims1_019c540a-9e2a-7b93-839d-eb4a15f610a8" xlink:to="loc_us-gaap_SupplementalInformationForPropertyCasualtyInsuranceUnderwritersCurrentYearClaimsAndClaimsAdjustmentExpense_019c540a-9e2a-733d-95b7-b63bb5ab8413" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SupplementalInformationForPropertyCasualtyInsuranceUnderwritersPriorYearClaimsAndClaimsAdjustmentExpense_019c540a-9e2a-79c3-b1e0-d6fab67b3b38" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_SupplementalInformationForPropertyCasualtyInsuranceUnderwritersPriorYearClaimsAndClaimsAdjustmentExpense"/>
    <link:calculationArc order="2" weight="1.0" xlink:arcrole="https://xbrl.org/2023/arcrole/summation-item" xlink:from="loc_us-gaap_LiabilityForUnpaidClaimsAndClaimsAdjustmentExpenseIncurredClaims1_019c540a-9e2a-7b93-839d-eb4a15f610a8" xlink:to="loc_us-gaap_SupplementalInformationForPropertyCasualtyInsuranceUnderwritersPriorYearClaimsAndClaimsAdjustmentExpense_019c540a-9e2a-79c3-b1e0-d6fab67b3b38" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PaymentsForLossesAndLossAdjustmentExpense_019c540a-9e2a-7ae7-bd5b-ba9e28aa5954" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_PaymentsForLossesAndLossAdjustmentExpense"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LiabilityForUnpaidClaimsAndClaimsAdjustmentExpenseClaimsPaidCurrentYear1_019c540a-9e2a-7e39-9c0e-5a10da7362fb" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_LiabilityForUnpaidClaimsAndClaimsAdjustmentExpenseClaimsPaidCurrentYear1"/>
    <link:calculationArc order="1" weight="1.0" xlink:arcrole="https://xbrl.org/2023/arcrole/summation-item" xlink:from="loc_us-gaap_PaymentsForLossesAndLossAdjustmentExpense_019c540a-9e2a-7ae7-bd5b-ba9e28aa5954" xlink:to="loc_us-gaap_LiabilityForUnpaidClaimsAndClaimsAdjustmentExpenseClaimsPaidCurrentYear1_019c540a-9e2a-7e39-9c0e-5a10da7362fb" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LiabilityForUnpaidClaimsAndClaimsAdjustmentExpenseClaimsPaidPriorYears1_019c540a-9e2a-7de7-9ac9-f707d62f3279" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_LiabilityForUnpaidClaimsAndClaimsAdjustmentExpenseClaimsPaidPriorYears1"/>
    <link:calculationArc order="2" weight="1.0" xlink:arcrole="https://xbrl.org/2023/arcrole/summation-item" xlink:from="loc_us-gaap_PaymentsForLossesAndLossAdjustmentExpense_019c540a-9e2a-7ae7-bd5b-ba9e28aa5954" xlink:to="loc_us-gaap_LiabilityForUnpaidClaimsAndClaimsAdjustmentExpenseClaimsPaidPriorYears1_019c540a-9e2a-7de7-9ac9-f707d62f3279" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_nmih_LiabilityForUnpaidClaimsAndClaimsAdjustmentExpenseClaimsPaidReinsuranceTerminations_019c540a-9e2a-781f-9a60-8ed9ed6a73c4" xlink:href="nmih-20260331.xsd#nmih_LiabilityForUnpaidClaimsAndClaimsAdjustmentExpenseClaimsPaidReinsuranceTerminations"/>
    <link:calculationArc order="3" weight="-1.0" xlink:arcrole="https://xbrl.org/2023/arcrole/summation-item" xlink:from="loc_us-gaap_PaymentsForLossesAndLossAdjustmentExpense_019c540a-9e2a-7ae7-bd5b-ba9e28aa5954" xlink:to="loc_nmih_LiabilityForUnpaidClaimsAndClaimsAdjustmentExpenseClaimsPaidReinsuranceTerminations_019c540a-9e2a-781f-9a60-8ed9ed6a73c4" xlink:type="arc"/>
  </link:calculationLink>
  <link:roleRef roleURI="http://www.nationalmi.com/role/EarningsperShareEPSScheduleofEarningsPerShareBasicandDilutedDetails" xlink:type="simple" xlink:href="nmih-20260331.xsd#EarningsperShareEPSScheduleofEarningsPerShareBasicandDilutedDetails"/>
  <link:calculationLink xlink:role="http://www.nationalmi.com/role/EarningsperShareEPSScheduleofEarningsPerShareBasicandDilutedDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_WeightedAverageNumberOfDilutedSharesOutstanding_019c540a-9e2a-7a0b-8ae8-77c245b8c27c" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_WeightedAverageNumberOfDilutedSharesOutstanding"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_WeightedAverageNumberOfSharesOutstandingBasic_019c540a-9e2a-7b1c-aba2-37d8cc1014d3" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_WeightedAverageNumberOfSharesOutstandingBasic"/>
    <link:calculationArc order="1" weight="1.0" xlink:arcrole="https://xbrl.org/2023/arcrole/summation-item" xlink:from="loc_us-gaap_WeightedAverageNumberOfDilutedSharesOutstanding_019c540a-9e2a-7a0b-8ae8-77c245b8c27c" xlink:to="loc_us-gaap_WeightedAverageNumberOfSharesOutstandingBasic_019c540a-9e2a-7b1c-aba2-37d8cc1014d3" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_WeightedAverageNumberDilutedSharesOutstandingAdjustment_019c540a-9e2a-73f8-b19b-d1b877355bff" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_WeightedAverageNumberDilutedSharesOutstandingAdjustment"/>
    <link:calculationArc order="2" weight="1.0" xlink:arcrole="https://xbrl.org/2023/arcrole/summation-item" xlink:from="loc_us-gaap_WeightedAverageNumberOfDilutedSharesOutstanding_019c540a-9e2a-7a0b-8ae8-77c245b8c27c" xlink:to="loc_us-gaap_WeightedAverageNumberDilutedSharesOutstandingAdjustment_019c540a-9e2a-73f8-b19b-d1b877355bff" xlink:type="arc"/>
  </link:calculationLink>
  <link:roleRef roleURI="http://www.nationalmi.com/role/RegulatoryInformationScheduleofStatutoryNetIncomelossSurplusContingencyReserveandRisktoCapitalRatioDetails" xlink:type="simple" xlink:href="nmih-20260331.xsd#RegulatoryInformationScheduleofStatutoryNetIncomelossSurplusContingencyReserveandRisktoCapitalRatioDetails"/>
  <link:calculationLink xlink:role="http://www.nationalmi.com/role/RegulatoryInformationScheduleofStatutoryNetIncomelossSurplusContingencyReserveandRisktoCapitalRatioDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_nmih_StatutoryAccountingPracticesStatutoryCapitalAndSurplusIncludingContingencyReserve_019c540a-9e2a-7c6c-b184-06a8174d559f" xlink:href="nmih-20260331.xsd#nmih_StatutoryAccountingPracticesStatutoryCapitalAndSurplusIncludingContingencyReserve"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatutoryAccountingPracticesStatutoryCapitalAndSurplusBalance_019c540a-9e2a-7329-9bec-1d193bbb36c7" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_StatutoryAccountingPracticesStatutoryCapitalAndSurplusBalance"/>
    <link:calculationArc order="1" weight="1.0" xlink:arcrole="https://xbrl.org/2023/arcrole/summation-item" xlink:from="loc_nmih_StatutoryAccountingPracticesStatutoryCapitalAndSurplusIncludingContingencyReserve_019c540a-9e2a-7c6c-b184-06a8174d559f" xlink:to="loc_us-gaap_StatutoryAccountingPracticesStatutoryCapitalAndSurplusBalance_019c540a-9e2a-7329-9bec-1d193bbb36c7" xlink:type="arc"/>
    <link:loc xlink:type="locator" xlink:label="loc_nmih_StatutoryAccountingPracticesContingencyReserve_019c540a-9e2a-790a-9205-ddfa18da7795" xlink:href="nmih-20260331.xsd#nmih_StatutoryAccountingPracticesContingencyReserve"/>
    <link:calculationArc order="2" weight="1.0" xlink:arcrole="https://xbrl.org/2023/arcrole/summation-item" xlink:from="loc_nmih_StatutoryAccountingPracticesStatutoryCapitalAndSurplusIncludingContingencyReserve_019c540a-9e2a-7c6c-b184-06a8174d559f" xlink:to="loc_nmih_StatutoryAccountingPracticesContingencyReserve_019c540a-9e2a-790a-9205-ddfa18da7795" xlink:type="arc"/>
  </link:calculationLink>
</link:linkbase>
