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        <ExplanationTxt>THE TRUST'S FINANCIAL STATEMENTS ARE INCLUDED AS PART OF AN OVERALL FINANCIAL AUDIT FOR THE UNITED STATES STEEL CORPORATION PLAN FOR RETIREE INSURANCE BENEFITS (THE "PLAN"). THE FOLLOWING FOOTNOTE IS INCLUDED IN THE CONSOLIDATED FINANCIAL STATEMENTS FOR THE PLAN: US GAAP REQUIRES PLAN MANAGEMENT TO EVALUATE TAX POSITIONS TAKEN BY THE PLAN AND TO RECOGNIZE A TAX LIABILITY (OR ASSET) IF THE PLAN HAS TAKEN AN UNCERTAIN POSITION THAT MORE LIKELY THAN NOT WOULD NOT BE SUSTAINED UPON EXAMINATION BY THE IRS. THE PLAN ADMINISTRATOR HAS ANALYZED THE TAX POSITIONS TAKEN BY THE PLAN AND HAS CONCLUDED THAT AS OF DECEMBER 31, 2023 AND 2022 THERE ARE NO UNCERTAIN POSITIONS TAKEN OR EXPECTED TO BE TAKEN THAT WOULD REQUIRE RECOGNITION OF A LIABILITY (OR ASSET) OR DISCLOSURE IN THE FINANCIAL STATEMENTS. THE PLAN IS SUBJECT TO ROUTINE AUDITS BY TAXING JURISDICTIONS. THE PLAN SPONSOR BELIEVES IT IS NO LONGER SUBJECT TO EXAMINATIONS BY FEDERAL TAXING JURISDICTIONS FOR YEARS PRIOR TO 2020.</ExplanationTxt>
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        <FormAndLineReferenceDesc>Form 990, Part VI, Line 12a Conflict of interest Policy</FormAndLineReferenceDesc>
        <ExplanationTxt>THE ORGANIZATION DOES NOT HAVE ITS OWN CONFLICT OF INTEREST POLICY BUT FOLLOWS THAT OF THE UNITED STATES STEEL AND CARNEGIE PENSION FUND ("PENSION FUND"). THE PENSION FUND ACTS AS THE INSTITUTIONAL TRUSTEE FOR THE UNITED STATES STEEL CORPORATION RETIREE INSURANCE BENEFITS TRUST. THE CHIEF COMPLIANCE OFFICER OF THE PENSION FUND PERFORMS AN ANNUAL COMPLIANCE REVIEW OF ITS CODE OF ETHICS, INCLUDING CONFLICT OF INTEREST. ANNUALLY, THE PENSION FUND EMPLOYEES CERTIFY COMPLIANCE WITH THE CODE OF ETHICS AND COMPLETE AN ETHICS QUESTIONNAIRE.</ExplanationTxt>
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      <SupplementalInformationDetail>
        <FormAndLineReferenceDesc>Form 990, Part VI, Line 13 whistle-blower policy</FormAndLineReferenceDesc>
        <ExplanationTxt>THE ORGANIZATION HAS NOT ADOPTED A WHISTLEBLOWER POLICY BUT FOLLOWS THE WHISTLEBLOWER POLICY OF THE UNITED STATES STEEL AND CARNEGIE PENSION FUND.</ExplanationTxt>
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        <ExplanationTxt>THE ORGANIZATION HAS NOT ADOPTED A DOCUMENT RETENTION AND DESTRUCTION POLICY BUT FOLLOWS THE DOCUMENT RETENTION AND DESTRUCTION POLICY OF THE UNITED STATES STEEL AND CARNEGIE PENSION FUND.</ExplanationTxt>
      </SupplementalInformationDetail>
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        <ExplanationTxt>THERE ARE NO COMMITTEES WITH THE AUTHORITY TO ACT ON BEHALF OF THE GOVERNING BODY. THEREFORE, THIS QUESTION IS NOT APPLICABLE AND HAS BEEN CHECKED NO IN ACCORDANCE WITH THE INSTRUCTIONS.</ExplanationTxt>
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      <SupplementalInformationDetail>
        <FormAndLineReferenceDesc>Form 990, Part VI, Line 11b Review of form 990 by governing body</FormAndLineReferenceDesc>
        <ExplanationTxt>THE FORM 990 IS PREPARED BY AN INDEPENDENT CPA FIRM. PRIOR TO ITS SUBMISSION TO THE INTERNAL REVENUE SERVICE, FORM 990 IS REVIEWED AND APPROVED BY THE BENEFITS ACCOUNTING GROUP WITHIN THE UNITED STATES STEEL AND CARNEGIE PENSION FUND.</ExplanationTxt>
      </SupplementalInformationDetail>
      <SupplementalInformationDetail>
        <FormAndLineReferenceDesc>Form 990, Part VI, Line 19 Required documents available to the public</FormAndLineReferenceDesc>
        <ExplanationTxt>A COPY OF THE ORGANIZATION'S GOVERNING DOCUMENTS AND FINANCIAL STATEMENTS ARE AVAILABLE TO THE PUBLIC UPON REQUEST TO THE EXTENT SUCH INSPECTION IS REQUIRED BY LAW.</ExplanationTxt>
      </SupplementalInformationDetail>
      <SupplementalInformationDetail>
        <FormAndLineReferenceDesc>Form 990, Part X, Line 25 Other Liabilities</FormAndLineReferenceDesc>
        <ExplanationTxt>LIABILITIES NOT REPORTED ON THE FINANCIAL STATEMENTS. THE FOLLOWING FOOTNOTE IS INCLUDED IN THE CONSOLIDATED FINANCIAL STATEMENTS FOR THE PLAN: CLAIMS INCURRED BUT NOT REPORTED TO THE PLAN REPRESENT AN ESTIMATE OF CLAIMS NOT PROCESSED AT THE END OF THE YEAR AND ARE ESTIMATED BY MANAGEMENT UTILIZING INFORMATION OBTAINED FROM THE INSURANCE COMPANIES. THESE AMOUNTS ARE PAID BY THE PLAN ONLY IF CLAIMS ARE SUBMITTED AND APPROVED FOR PAYMENT.</ExplanationTxt>
      </SupplementalInformationDetail>
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    <IRS990ScheduleR documentId="IRS990ScheduleR" softwareId="23017437" softwareVersionNum="2023v5.1">
      <IdRelatedOrgTxblCorpTrGrp>
        <RelatedOrganizationName>
          <BusinessNameLine1Txt>United States Steel Corporation</BusinessNameLine1Txt>
        </RelatedOrganizationName>
        <USAddress>
          <AddressLine1Txt>600 GRANT STREET</AddressLine1Txt>
          <CityNm>PITTSBURGH</CityNm>
          <StateAbbreviationCd>PA</StateAbbreviationCd>
          <ZIPCd>15219</ZIPCd>
        </USAddress>
        <EIN>251897152</EIN>
        <PrimaryActivitiesTxt>MANUFACTURING</PrimaryActivitiesTxt>
        <LegalDomicileStateCd>PA</LegalDomicileStateCd>
        <DirectControllingEntityName>
          <BusinessNameLine1Txt>NA</BusinessNameLine1Txt>
        </DirectControllingEntityName>
        <EntityTypeTxt>C Corporation</EntityTypeTxt>
        <ShareOfTotalIncomeAmt>0</ShareOfTotalIncomeAmt>
        <ShareOfEOYAssetsAmt>0</ShareOfEOYAssetsAmt>
        <OwnershipPct>0</OwnershipPct>
        <ControlledOrganizationInd>false</ControlledOrganizationInd>
      </IdRelatedOrgTxblCorpTrGrp>
      <ReceiptOfIntAnntsRntsRyltsInd>false</ReceiptOfIntAnntsRntsRyltsInd>
      <GiftGrntOrCapContriToOthOrgInd>false</GiftGrntOrCapContriToOthOrgInd>
      <GiftGrntCapContriFromOthOrgInd>false</GiftGrntCapContriFromOthOrgInd>
      <LoansOrGuaranteesToOtherOrgInd>false</LoansOrGuaranteesToOtherOrgInd>
      <LoansOrGuaranteesFromOthOrgInd>false</LoansOrGuaranteesFromOthOrgInd>
      <DivRelatedOrganizationInd>false</DivRelatedOrganizationInd>
      <AssetSaleToOtherOrgInd>false</AssetSaleToOtherOrgInd>
      <AssetPurchaseFromOtherOrgInd>false</AssetPurchaseFromOtherOrgInd>
      <AssetExchangeInd>false</AssetExchangeInd>
      <RentalOfFacilitiesToOthOrgInd>false</RentalOfFacilitiesToOthOrgInd>
      <RentalOfFcltsFromOthOrgInd>false</RentalOfFcltsFromOthOrgInd>
      <PerformOfServicesForOthOrgInd>false</PerformOfServicesForOthOrgInd>
      <PerformOfServicesByOtherOrgInd>false</PerformOfServicesByOtherOrgInd>
      <SharingOfFacilitiesInd>false</SharingOfFacilitiesInd>
      <PaidEmployeesSharingInd>false</PaidEmployeesSharingInd>
      <ReimbursementPaidToOtherOrgInd>false</ReimbursementPaidToOtherOrgInd>
      <ReimbursementPaidByOtherOrgInd>false</ReimbursementPaidByOtherOrgInd>
      <TransferToOtherOrgInd>false</TransferToOtherOrgInd>
      <TransferFromOtherOrgInd>false</TransferFromOtherOrgInd>
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