﻿<?xml version="1.0" encoding="utf-8"?>
<Return xmlns="http://www.irs.gov/efile" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://www.irs.gov/efile" returnVersion="2024v5.5">
  <ReturnHeader binaryAttachmentCnt="0">
    <ReturnTs>2026-08-17T07:43:37-05:00</ReturnTs>
    <TaxPeriodEndDt>2025-09-30</TaxPeriodEndDt>
    <PreparerFirmGrp>
      <PreparerFirmEIN>135565207</PreparerFirmEIN>
      <PreparerFirmName>
        <BusinessNameLine1Txt>KPMG LLP</BusinessNameLine1Txt>
      </PreparerFirmName>
      <PreparerUSAddress>
        <AddressLine1Txt>TWO MANHATTAN WEST 375 9TH AVENUE</AddressLine1Txt>
        <CityNm>NEW YORK</CityNm>
        <StateAbbreviationCd>NY</StateAbbreviationCd>
        <ZIPCd>10001</ZIPCd>
      </PreparerUSAddress>
    </PreparerFirmGrp>
    <ReturnTypeCd>990</ReturnTypeCd>
    <TaxPeriodBeginDt>2024-10-01</TaxPeriodBeginDt>
    <Filer>
      <EIN>871371777</EIN>
      <BusinessName>
        <BusinessNameLine1Txt>CONNECTICUT PROTON THERAPY CENTER LLC</BusinessNameLine1Txt>
      </BusinessName>
      <BusinessNameControlTxt>CONN</BusinessNameControlTxt>
      <PhoneNum>2036889585</PhoneNum>
      <USAddress>
        <AddressLine1Txt>932 NORTHROP ROAD</AddressLine1Txt>
        <CityNm>WALLINGFORD</CityNm>
        <StateAbbreviationCd>CT</StateAbbreviationCd>
        <ZIPCd>06492</ZIPCd>
      </USAddress>
    </Filer>
    <BusinessOfficerGrp>
      <PersonNm>LORI PICKENS</PersonNm>
      <PersonTitleTxt>PRESIDENT</PersonTitleTxt>
      <PhoneNum>2036889585</PhoneNum>
      <SignatureDt>2026-08-17</SignatureDt>
      <DiscussWithPaidPreparerInd>0</DiscussWithPaidPreparerInd>
    </BusinessOfficerGrp>
    <IRSResponsiblePrtyInfoCurrInd>1</IRSResponsiblePrtyInfoCurrInd>
    <PreparerPersonGrp>
      <PreparerPersonNm>EVAN W SEEKAMP</PreparerPersonNm>
      <PTIN>P01907071</PTIN>
      <PhoneNum>2127589700</PhoneNum>
    </PreparerPersonGrp>
    <TaxYr>2024</TaxYr>
    <BuildTS>2025-03-06 01:10:19Z</BuildTS>
  </ReturnHeader>
  <ReturnData documentCnt="4">
    <IRS990 documentId="RetDoc1038000001" referenceDocumentId="RetDoc1044400001">
      <PrincipalOfficerNm>LORI PICKENS</PrincipalOfficerNm>
      <USAddress>
        <AddressLine1Txt>789 HOWARD AVENUE</AddressLine1Txt>
        <CityNm>NEW HAVEN</CityNm>
        <StateAbbreviationCd>CT</StateAbbreviationCd>
        <ZIPCd>06519</ZIPCd>
      </USAddress>
      <GrossReceiptsAmt>194936</GrossReceiptsAmt>
      <GroupReturnForAffiliatesInd>0</GroupReturnForAffiliatesInd>
      <Organization501c3Ind>X</Organization501c3Ind>
      <WebsiteAddressTxt>N/A</WebsiteAddressTxt>
      <TypeOfOrganizationOtherInd>X</TypeOfOrganizationOtherInd>
      <OtherOrganizationDsc>LLC</OtherOrganizationDsc>
      <FormationYr>2019</FormationYr>
      <LegalDomicileStateCd>CT</LegalDomicileStateCd>
      <ActivityOrMissionDesc>TO DEVELOP AND OPERATE A PROTON THERAPY CENTER TO PROVIDE RADIATION MODALITY TO CLINICALLY APPROPRIATE PATIENTS IN THE STATE OF CONNECTICUT AND BEYOND.</ActivityOrMissionDesc>
      <VotingMembersGoverningBodyCnt>4</VotingMembersGoverningBodyCnt>
      <VotingMembersIndependentCnt>4</VotingMembersIndependentCnt>
      <TotalEmployeeCnt>0</TotalEmployeeCnt>
      <TotalVolunteersCnt>4</TotalVolunteersCnt>
      <TotalGrossUBIAmt>0</TotalGrossUBIAmt>
      <NetUnrelatedBusTxblIncmAmt>0</NetUnrelatedBusTxblIncmAmt>
      <PYContributionsGrantsAmt>0</PYContributionsGrantsAmt>
      <CYContributionsGrantsAmt>0</CYContributionsGrantsAmt>
      <PYProgramServiceRevenueAmt>0</PYProgramServiceRevenueAmt>
      <CYProgramServiceRevenueAmt>0</CYProgramServiceRevenueAmt>
      <PYInvestmentIncomeAmt>0</PYInvestmentIncomeAmt>
      <CYInvestmentIncomeAmt>194936</CYInvestmentIncomeAmt>
      <PYOtherRevenueAmt>0</PYOtherRevenueAmt>
      <CYOtherRevenueAmt>0</CYOtherRevenueAmt>
      <PYTotalRevenueAmt>0</PYTotalRevenueAmt>
      <CYTotalRevenueAmt>194936</CYTotalRevenueAmt>
      <PYGrantsAndSimilarPaidAmt>0</PYGrantsAndSimilarPaidAmt>
      <CYGrantsAndSimilarPaidAmt>0</CYGrantsAndSimilarPaidAmt>
      <PYBenefitsPaidToMembersAmt>0</PYBenefitsPaidToMembersAmt>
      <CYBenefitsPaidToMembersAmt>0</CYBenefitsPaidToMembersAmt>
      <PYSalariesCompEmpBnftPaidAmt>0</PYSalariesCompEmpBnftPaidAmt>
      <CYSalariesCompEmpBnftPaidAmt>0</CYSalariesCompEmpBnftPaidAmt>
      <PYTotalProfFndrsngExpnsAmt>0</PYTotalProfFndrsngExpnsAmt>
      <CYTotalProfFndrsngExpnsAmt>0</CYTotalProfFndrsngExpnsAmt>
      <CYTotalFundraisingExpenseAmt>0</CYTotalFundraisingExpenseAmt>
      <PYOtherExpensesAmt>1847508</PYOtherExpensesAmt>
      <CYOtherExpensesAmt>373965</CYOtherExpensesAmt>
      <PYTotalExpensesAmt>1847508</PYTotalExpensesAmt>
      <CYTotalExpensesAmt>373965</CYTotalExpensesAmt>
      <PYRevenuesLessExpensesAmt>-1847508</PYRevenuesLessExpensesAmt>
      <CYRevenuesLessExpensesAmt>-179029</CYRevenuesLessExpensesAmt>
      <TotalAssetsBOYAmt>40389097</TotalAssetsBOYAmt>
      <TotalAssetsEOYAmt>73318889</TotalAssetsEOYAmt>
      <TotalLiabilitiesBOYAmt>39789027</TotalLiabilitiesBOYAmt>
      <TotalLiabilitiesEOYAmt>72897848</TotalLiabilitiesEOYAmt>
      <NetAssetsOrFundBalancesBOYAmt>600070</NetAssetsOrFundBalancesBOYAmt>
      <NetAssetsOrFundBalancesEOYAmt>421041</NetAssetsOrFundBalancesEOYAmt>
      <MissionDesc>TO DEVELOP AND OPERATE A PROTON THERAPY CENTER TO PROVIDE RADIATION MODALITY TO CLINICALLY APPROPRIATE PATIENTS IN THE STATE OF CONNECTICUT AND BEYOND.</MissionDesc>
      <SignificantNewProgramSrvcInd>0</SignificantNewProgramSrvcInd>
      <SignificantChangeInd>0</SignificantChangeInd>
      <ExpenseAmt>373965</ExpenseAmt>
      <RevenueAmt>0</RevenueAmt>
      <Desc>TO DEVELOP AND OPERATE A PROTON THERAPY CENTER TO PROVIDE RADIATION MODALITY TO CLINICALLY APPROPRIATE PATIENTS IN THE STATE OF CONNECTICUT AND BEYOND.</Desc>
      <TotalProgramServiceExpensesAmt>373965</TotalProgramServiceExpensesAmt>
      <DescribedInSection501c3Ind referenceDocumentId="RetDoc1039100001">1</DescribedInSection501c3Ind>
      <ScheduleBRequiredInd>0</ScheduleBRequiredInd>
      <PoliticalCampaignActyInd>0</PoliticalCampaignActyInd>
      <LobbyingActivitiesInd>0</LobbyingActivitiesInd>
      <SubjectToProxyTaxInd>0</SubjectToProxyTaxInd>
      <DonorAdvisedFundInd referenceDocumentId="RetDoc1040000001">0</DonorAdvisedFundInd>
      <ConservationEasementsInd referenceDocumentId="RetDoc1040000001">0</ConservationEasementsInd>
      <CollectionsOfArtInd referenceDocumentId="RetDoc1040000001">0</CollectionsOfArtInd>
      <CreditCounselingInd referenceDocumentId="RetDoc1040000001">0</CreditCounselingInd>
      <DonorRstrOrQuasiEndowmentsInd>0</DonorRstrOrQuasiEndowmentsInd>
      <ReportLandBuildingEquipmentInd referenceDocumentId="RetDoc1040000001">1</ReportLandBuildingEquipmentInd>
      <ReportInvestmentsOtherSecInd referenceDocumentId="RetDoc1040000001">0</ReportInvestmentsOtherSecInd>
      <ReportProgramRelatedInvstInd referenceDocumentId="RetDoc1040000001">0</ReportProgramRelatedInvstInd>
      <ReportOtherAssetsInd referenceDocumentId="RetDoc1040000001">0</ReportOtherAssetsInd>
      <ReportOtherLiabilitiesInd referenceDocumentId="RetDoc1040000001">1</ReportOtherLiabilitiesInd>
      <IncludeFIN48FootnoteInd referenceDocumentId="RetDoc1040000001">0</IncludeFIN48FootnoteInd>
      <IndependentAuditFinclStmtInd referenceDocumentId="RetDoc1040000001">1</IndependentAuditFinclStmtInd>
      <ConsolidatedAuditFinclStmtInd referenceDocumentId="RetDoc1040000001">0</ConsolidatedAuditFinclStmtInd>
      <SchoolOperatingInd>0</SchoolOperatingInd>
      <ForeignOfficeInd>0</ForeignOfficeInd>
      <ForeignActivitiesInd>0</ForeignActivitiesInd>
      <MoreThan5000KToOrgInd>0</MoreThan5000KToOrgInd>
      <MoreThan5000KToIndividualsInd>0</MoreThan5000KToIndividualsInd>
      <ProfessionalFundraisingInd>0</ProfessionalFundraisingInd>
      <FundraisingActivitiesInd>0</FundraisingActivitiesInd>
      <GamingActivitiesInd>0</GamingActivitiesInd>
      <OperateHospitalInd>0</OperateHospitalInd>
      <GrantsToOrganizationsInd>0</GrantsToOrganizationsInd>
      <GrantsToIndividualsInd>0</GrantsToIndividualsInd>
      <ScheduleJRequiredInd>0</ScheduleJRequiredInd>
      <TaxExemptBondsInd>0</TaxExemptBondsInd>
      <EngagedInExcessBenefitTransInd>0</EngagedInExcessBenefitTransInd>
      <PYExcessBenefitTransInd>0</PYExcessBenefitTransInd>
      <LoanOutstandingInd>0</LoanOutstandingInd>
      <GrantToRelatedPersonInd>0</GrantToRelatedPersonInd>
      <BusinessRlnWithOrgMemInd>0</BusinessRlnWithOrgMemInd>
      <BusinessRlnWithFamMemInd>0</BusinessRlnWithFamMemInd>
      <BusinessRlnWith35CtrlEntInd>0</BusinessRlnWith35CtrlEntInd>
      <DeductibleNonCashContriInd>0</DeductibleNonCashContriInd>
      <DeductibleArtContributionInd>0</DeductibleArtContributionInd>
      <TerminateOperationsInd>0</TerminateOperationsInd>
      <PartialLiquidationInd>0</PartialLiquidationInd>
      <DisregardedEntityInd>0</DisregardedEntityInd>
      <RelatedEntityInd>0</RelatedEntityInd>
      <RelatedOrganizationCtrlEntInd>0</RelatedOrganizationCtrlEntInd>
      <TrnsfrExmptNonChrtblRltdOrgInd>0</TrnsfrExmptNonChrtblRltdOrgInd>
      <ActivitiesConductedPrtshpInd>0</ActivitiesConductedPrtshpInd>
      <ScheduleORequiredInd>1</ScheduleORequiredInd>
      <IRPDocumentCnt>7</IRPDocumentCnt>
      <IRPDocumentW2GCnt>0</IRPDocumentW2GCnt>
      <EmployeeCnt>0</EmployeeCnt>
      <UnrelatedBusIncmOverLimitInd>0</UnrelatedBusIncmOverLimitInd>
      <ForeignFinancialAccountInd>0</ForeignFinancialAccountInd>
      <ProhibitedTaxShelterTransInd>0</ProhibitedTaxShelterTransInd>
      <TaxablePartyNotificationInd>0</TaxablePartyNotificationInd>
      <NondeductibleContributionsInd>0</NondeductibleContributionsInd>
      <QuidProQuoContributionsInd>0</QuidProQuoContributionsInd>
      <Form8282PropertyDisposedOfInd>0</Form8282PropertyDisposedOfInd>
      <RcvFndsToPayPrsnlBnftCntrctInd>0</RcvFndsToPayPrsnlBnftCntrctInd>
      <PayPremiumsPrsnlBnftCntrctInd>0</PayPremiumsPrsnlBnftCntrctInd>
      <IndoorTanningServicesInd>0</IndoorTanningServicesInd>
      <SubjToTaxRmnrtnExPrchtPymtInd>0</SubjToTaxRmnrtnExPrchtPymtInd>
      <SubjectToExcsTaxNetInvstIncInd>0</SubjectToExcsTaxNetInvstIncInd>
      <InfoInScheduleOPartVIInd>X</InfoInScheduleOPartVIInd>
      <GoverningBodyVotingMembersCnt>4</GoverningBodyVotingMembersCnt>
      <IndependentVotingMemberCnt>4</IndependentVotingMemberCnt>
      <FamilyOrBusinessRlnInd>1</FamilyOrBusinessRlnInd>
      <DelegationOfMgmtDutiesInd>1</DelegationOfMgmtDutiesInd>
      <ChangeToOrgDocumentsInd>0</ChangeToOrgDocumentsInd>
      <MaterialDiversionOrMisuseInd>0</MaterialDiversionOrMisuseInd>
      <MembersOrStockholdersInd>1</MembersOrStockholdersInd>
      <ElectionOfBoardMembersInd>1</ElectionOfBoardMembersInd>
      <DecisionsSubjectToApprovaInd>1</DecisionsSubjectToApprovaInd>
      <MinutesOfGoverningBodyInd>1</MinutesOfGoverningBodyInd>
      <MinutesOfCommitteesInd>1</MinutesOfCommitteesInd>
      <OfficerMailingAddressInd>0</OfficerMailingAddressInd>
      <LocalChaptersInd>0</LocalChaptersInd>
      <Form990ProvidedToGvrnBodyInd>1</Form990ProvidedToGvrnBodyInd>
      <ConflictOfInterestPolicyInd>0</ConflictOfInterestPolicyInd>
      <WhistleblowerPolicyInd>0</WhistleblowerPolicyInd>
      <DocumentRetentionPolicyInd>0</DocumentRetentionPolicyInd>
      <CompensationProcessCEOInd>0</CompensationProcessCEOInd>
      <CompensationProcessOtherInd>0</CompensationProcessOtherInd>
      <InvestmentInJointVentureInd>0</InvestmentInJointVentureInd>
      <UponRequestInd>X</UponRequestInd>
      <BooksInCareOfDetail>
        <BusinessName>
          <BusinessNameLine1Txt>VERNETTE D GRAY</BusinessNameLine1Txt>
        </BusinessName>
        <PhoneNum>2036889585</PhoneNum>
        <USAddress>
          <AddressLine1Txt>789 HOWARD AVE</AddressLine1Txt>
          <CityNm>NEW HAVEN</CityNm>
          <StateAbbreviationCd>CT</StateAbbreviationCd>
          <ZIPCd>06519</ZIPCd>
        </USAddress>
      </BooksInCareOfDetail>
      <NoListedPersonsCompensatedInd>X</NoListedPersonsCompensatedInd>
      <Form990PartVIISectionAGrp>
        <PersonNm>GERALD BOISVERT</PersonNm>
        <TitleTxt>TREASURER/MEMBER</TitleTxt>
        <AverageHoursPerWeekRt>1.00</AverageHoursPerWeekRt>
        <AverageHoursPerWeekRltdOrgRt>0.00</AverageHoursPerWeekRltdOrgRt>
        <IndividualTrusteeOrDirectorInd>X</IndividualTrusteeOrDirectorInd>
        <OfficerInd>X</OfficerInd>
        <ReportableCompFromOrgAmt>0</ReportableCompFromOrgAmt>
        <ReportableCompFromRltdOrgAmt>0</ReportableCompFromRltdOrgAmt>
        <OtherCompensationAmt>0</OtherCompensationAmt>
      </Form990PartVIISectionAGrp>
      <Form990PartVIISectionAGrp>
        <PersonNm>KRISTI GAFFORD</PersonNm>
        <TitleTxt>CHAIR/MEMBER</TitleTxt>
        <AverageHoursPerWeekRt>1.00</AverageHoursPerWeekRt>
        <AverageHoursPerWeekRltdOrgRt>0.00</AverageHoursPerWeekRltdOrgRt>
        <IndividualTrusteeOrDirectorInd>X</IndividualTrusteeOrDirectorInd>
        <OfficerInd>X</OfficerInd>
        <ReportableCompFromOrgAmt>0</ReportableCompFromOrgAmt>
        <ReportableCompFromRltdOrgAmt>0</ReportableCompFromRltdOrgAmt>
        <OtherCompensationAmt>0</OtherCompensationAmt>
      </Form990PartVIISectionAGrp>
      <Form990PartVIISectionAGrp>
        <PersonNm>ELIZABETH HERBERT</PersonNm>
        <TitleTxt>SECRETARY</TitleTxt>
        <AverageHoursPerWeekRt>1.00</AverageHoursPerWeekRt>
        <AverageHoursPerWeekRltdOrgRt>0.00</AverageHoursPerWeekRltdOrgRt>
        <OfficerInd>X</OfficerInd>
        <ReportableCompFromOrgAmt>0</ReportableCompFromOrgAmt>
        <ReportableCompFromRltdOrgAmt>0</ReportableCompFromRltdOrgAmt>
        <OtherCompensationAmt>0</OtherCompensationAmt>
      </Form990PartVIISectionAGrp>
      <Form990PartVIISectionAGrp>
        <PersonNm>GAIL KOSYLA</PersonNm>
        <TitleTxt>MEMBER</TitleTxt>
        <AverageHoursPerWeekRt>1.00</AverageHoursPerWeekRt>
        <AverageHoursPerWeekRltdOrgRt>0.00</AverageHoursPerWeekRltdOrgRt>
        <IndividualTrusteeOrDirectorInd>X</IndividualTrusteeOrDirectorInd>
        <ReportableCompFromOrgAmt>0</ReportableCompFromOrgAmt>
        <ReportableCompFromRltdOrgAmt>0</ReportableCompFromRltdOrgAmt>
        <OtherCompensationAmt>0</OtherCompensationAmt>
      </Form990PartVIISectionAGrp>
      <Form990PartVIISectionAGrp>
        <PersonNm>LORI PICKENS</PersonNm>
        <TitleTxt>PRESIDENT/MEMBER</TitleTxt>
        <AverageHoursPerWeekRt>1.00</AverageHoursPerWeekRt>
        <AverageHoursPerWeekRltdOrgRt>0.00</AverageHoursPerWeekRltdOrgRt>
        <IndividualTrusteeOrDirectorInd>X</IndividualTrusteeOrDirectorInd>
        <OfficerInd>X</OfficerInd>
        <ReportableCompFromOrgAmt>0</ReportableCompFromOrgAmt>
        <ReportableCompFromRltdOrgAmt>0</ReportableCompFromRltdOrgAmt>
        <OtherCompensationAmt>0</OtherCompensationAmt>
      </Form990PartVIISectionAGrp>
      <TotalReportableCompFromOrgAmt>0</TotalReportableCompFromOrgAmt>
      <TotReportableCompRltdOrgAmt>0</TotReportableCompRltdOrgAmt>
      <TotalOtherCompensationAmt>0</TotalOtherCompensationAmt>
      <IndivRcvdGreaterThan100KCnt>0</IndivRcvdGreaterThan100KCnt>
      <FormerOfcrEmployeesListedInd>0</FormerOfcrEmployeesListedInd>
      <TotalCompGreaterThan150KInd>0</TotalCompGreaterThan150KInd>
      <CompensationFromOtherSrcsInd>0</CompensationFromOtherSrcsInd>
      <CntrctRcvdGreaterThan100KCnt>0</CntrctRcvdGreaterThan100KCnt>
      <InvestmentIncomeGrp>
        <TotalRevenueColumnAmt>194936</TotalRevenueColumnAmt>
        <ExclusionAmt>194936</ExclusionAmt>
      </InvestmentIncomeGrp>
      <TotalRevenueGrp>
        <TotalRevenueColumnAmt>194936</TotalRevenueColumnAmt>
        <RelatedOrExemptFuncIncomeAmt>0</RelatedOrExemptFuncIncomeAmt>
        <UnrelatedBusinessRevenueAmt>0</UnrelatedBusinessRevenueAmt>
        <ExclusionAmt>194936</ExclusionAmt>
      </TotalRevenueGrp>
      <InfoInScheduleOPartIXInd>X</InfoInScheduleOPartIXInd>
      <FeesForServicesOtherGrp>
        <TotalAmt>197907</TotalAmt>
        <ProgramServicesAmt>197907</ProgramServicesAmt>
      </FeesForServicesOtherGrp>
      <InterestGrp>
        <TotalAmt>176058</TotalAmt>
        <ProgramServicesAmt>176058</ProgramServicesAmt>
      </InterestGrp>
      <TotalFunctionalExpensesGrp>
        <TotalAmt>373965</TotalAmt>
        <ProgramServicesAmt>373965</ProgramServicesAmt>
        <ManagementAndGeneralAmt>0</ManagementAndGeneralAmt>
        <FundraisingAmt>0</FundraisingAmt>
      </TotalFunctionalExpensesGrp>
      <InfoInScheduleOPartXInd>X</InfoInScheduleOPartXInd>
      <SavingsAndTempCashInvstGrp>
        <BOYAmt>6305794</BOYAmt>
        <EOYAmt>3484721</EOYAmt>
      </SavingsAndTempCashInvstGrp>
      <LandBldgEquipCostOrOtherBssAmt>69834168</LandBldgEquipCostOrOtherBssAmt>
      <LandBldgEquipAccumDeprecAmt>0</LandBldgEquipAccumDeprecAmt>
      <LandBldgEquipBasisNetGrp>
        <BOYAmt>34083303</BOYAmt>
        <EOYAmt>69834168</EOYAmt>
      </LandBldgEquipBasisNetGrp>
      <TotalAssetsGrp>
        <BOYAmt>40389097</BOYAmt>
        <EOYAmt>73318889</EOYAmt>
      </TotalAssetsGrp>
      <AccountsPayableAccrExpnssGrp>
        <BOYAmt>1518313</BOYAmt>
        <EOYAmt>4922419</EOYAmt>
      </AccountsPayableAccrExpnssGrp>
      <UnsecuredNotesLoansPayableGrp>
        <BOYAmt>37685738</BOYAmt>
        <EOYAmt>65580617</EOYAmt>
      </UnsecuredNotesLoansPayableGrp>
      <OtherLiabilitiesGrp>
        <BOYAmt>584976</BOYAmt>
        <EOYAmt>2394812</EOYAmt>
      </OtherLiabilitiesGrp>
      <TotalLiabilitiesGrp>
        <BOYAmt>39789027</BOYAmt>
        <EOYAmt>72897848</EOYAmt>
      </TotalLiabilitiesGrp>
      <OrgDoesNotFollowFASB117Ind>X</OrgDoesNotFollowFASB117Ind>
      <CapStkTrPrinCurrentFundsGrp>
        <BOYAmt>2500740</BOYAmt>
        <EOYAmt>600070</EOYAmt>
      </CapStkTrPrinCurrentFundsGrp>
      <PdInCapSrplsLandBldgEqpFundGrp>
        <BOYAmt>0</BOYAmt>
        <EOYAmt>0</EOYAmt>
      </PdInCapSrplsLandBldgEqpFundGrp>
      <RtnEarnEndowmentIncmOthFndsGrp>
        <BOYAmt>-1900670</BOYAmt>
        <EOYAmt>-179029</EOYAmt>
      </RtnEarnEndowmentIncmOthFndsGrp>
      <TotalNetAssetsFundBalanceGrp>
        <BOYAmt>600070</BOYAmt>
        <EOYAmt>421041</EOYAmt>
      </TotalNetAssetsFundBalanceGrp>
      <TotLiabNetAssetsFundBalanceGrp>
        <BOYAmt>40389097</BOYAmt>
        <EOYAmt>73318889</EOYAmt>
      </TotLiabNetAssetsFundBalanceGrp>
      <ReconcilationRevenueExpnssAmt>-179029</ReconcilationRevenueExpnssAmt>
      <OtherChangesInNetAssetsAmt>0</OtherChangesInNetAssetsAmt>
      <MethodOfAccountingAccrualInd>X</MethodOfAccountingAccrualInd>
      <AccountantCompileOrReviewInd>0</AccountantCompileOrReviewInd>
      <FSAuditedInd>1</FSAuditedInd>
      <FSAuditedBasisGrp>
        <SeparateBasisFinclStmtInd>X</SeparateBasisFinclStmtInd>
      </FSAuditedBasisGrp>
      <AuditCommitteeInd>0</AuditCommitteeInd>
      <FederalGrantAuditRequiredInd>0</FederalGrantAuditRequiredInd>
    </IRS990>
    <IRS990ScheduleA documentId="RetDoc1039100001">
      <PubliclySupportedOrg509a2Ind>X</PubliclySupportedOrg509a2Ind>
      <GiftsGrantsContrisRcvd509Grp>
        <CurrentTaxYearMinus1YearAmt>0</CurrentTaxYearMinus1YearAmt>
        <CurrentTaxYearAmt>0</CurrentTaxYearAmt>
      </GiftsGrantsContrisRcvd509Grp>
      <GrossReceiptsNonUnrltBusGrp>
        <CurrentTaxYearMinus1YearAmt>0</CurrentTaxYearMinus1YearAmt>
        <CurrentTaxYearAmt>0</CurrentTaxYearAmt>
      </GrossReceiptsNonUnrltBusGrp>
      <TaxRevLeviedOrgnztnlBnft509Grp>
        <CurrentTaxYearMinus1YearAmt>0</CurrentTaxYearMinus1YearAmt>
        <CurrentTaxYearAmt>0</CurrentTaxYearAmt>
      </TaxRevLeviedOrgnztnlBnft509Grp>
      <GovtFurnSrvcFcltsVl509Grp>
        <CurrentTaxYearMinus1YearAmt>0</CurrentTaxYearMinus1YearAmt>
        <CurrentTaxYearAmt>0</CurrentTaxYearAmt>
      </GovtFurnSrvcFcltsVl509Grp>
      <PublicSupportTotal509Amt>0</PublicSupportTotal509Amt>
      <GrossInvestmentIncome509Grp>
        <CurrentTaxYearMinus1YearAmt>0</CurrentTaxYearMinus1YearAmt>
        <CurrentTaxYearAmt>194936</CurrentTaxYearAmt>
        <TotalAmt>194936</TotalAmt>
      </GrossInvestmentIncome509Grp>
      <InvestmentIncomeAndUBTIGrp>
        <CurrentTaxYearAmt>194936</CurrentTaxYearAmt>
        <TotalAmt>194936</TotalAmt>
      </InvestmentIncomeAndUBTIGrp>
      <NetIncomeFromOtherUBIGrp>
        <CurrentTaxYearMinus1YearAmt>0</CurrentTaxYearMinus1YearAmt>
        <CurrentTaxYearAmt>0</CurrentTaxYearAmt>
      </NetIncomeFromOtherUBIGrp>
      <TotalSupportCalendarYearGrp>
        <CurrentTaxYearAmt>194936</CurrentTaxYearAmt>
        <TotalAmt>194936</TotalAmt>
      </TotalSupportCalendarYearGrp>
      <First5Years509Ind>X</First5Years509Ind>
    </IRS990ScheduleA>
    <IRS990ScheduleD documentId="RetDoc1040000001">
      <LandGrp>
        <OtherCostOrOtherBasisAmt>1800000</OtherCostOrOtherBasisAmt>
        <BookValueAmt>1800000</BookValueAmt>
      </LandGrp>
      <BuildingsGrp>
        <OtherCostOrOtherBasisAmt>44301484</OtherCostOrOtherBasisAmt>
        <BookValueAmt>44301484</BookValueAmt>
      </BuildingsGrp>
      <EquipmentGrp>
        <OtherCostOrOtherBasisAmt>23732684</OtherCostOrOtherBasisAmt>
        <BookValueAmt>23732684</BookValueAmt>
      </EquipmentGrp>
      <TotalBookValueLandBuildingsAmt>69834168</TotalBookValueLandBuildingsAmt>
      <OtherLiabilitiesOrgGrp>
        <Desc>ACCRUED INTEREST</Desc>
        <Amt>2394812</Amt>
      </OtherLiabilitiesOrgGrp>
      <TotalLiabilityAmt>2394812</TotalLiabilityAmt>
      <TotalRevEtcAuditedFinclStmtAmt>194936</TotalRevEtcAuditedFinclStmtAmt>
      <RevenueNotReportedAmt>0</RevenueNotReportedAmt>
      <RevenueSubtotalAmt>194936</RevenueSubtotalAmt>
      <RevenueNotReportedFinclStmtAmt>0</RevenueNotReportedFinclStmtAmt>
      <TotalRevenuePerForm990Amt>194936</TotalRevenuePerForm990Amt>
      <TotExpnsEtcAuditedFinclStmtAmt>373965</TotExpnsEtcAuditedFinclStmtAmt>
      <ExpensesNotReportedAmt>0</ExpensesNotReportedAmt>
      <ExpensesSubtotalAmt>373965</ExpensesSubtotalAmt>
      <ExpensesNotRptFinclStmtAmt>0</ExpensesNotRptFinclStmtAmt>
      <TotalExpensesPerForm990Amt>373965</TotalExpensesPerForm990Amt>
    </IRS990ScheduleD>
    <IRS990ScheduleO documentId="RetDoc1044400001">
      <SupplementalInformationDetail>
        <FormAndLineReferenceDesc>FORM 990, PART VI, SECTION A, LINE 2</FormAndLineReferenceDesc>
        <ExplanationTxt>TWO OF THE ORGANIZATION'S VOTING MEMBERS WHO SERVED DURING THE FISCAL YEAR ARE EMPLOYED BY YALE NEW HAVEN HEALTH SERVICES CORPORATION AND TWO OF THE ORGANIZATION'S VOTING MEMBERS ARE EMPLOYED BY HARTFORD HEALTHCARE CORPORATION.</ExplanationTxt>
      </SupplementalInformationDetail>
      <SupplementalInformationDetail>
        <FormAndLineReferenceDesc>FORM 990, PART VI, SECTION A, LINE 3</FormAndLineReferenceDesc>
        <ExplanationTxt>THE ORGANIZATION DELEGATED CONTROL OVER MANAGEMENT DUTIES TO PARTNERS IN HEALTHCARE TECHNOLOGY, LLC</ExplanationTxt>
      </SupplementalInformationDetail>
      <SupplementalInformationDetail>
        <FormAndLineReferenceDesc>FORM 990, PART VI, SECTION A, LINE 6</FormAndLineReferenceDesc>
        <ExplanationTxt>THE TWO MEMBERS ARE YALE NEW HAVEN HEALTH SERVICES CORPORATION AND HARTFORD HEALTHCARE CORPORATION.</ExplanationTxt>
      </SupplementalInformationDetail>
      <SupplementalInformationDetail>
        <FormAndLineReferenceDesc>FORM 990, PART VI, SECTION A, LINE 7A</FormAndLineReferenceDesc>
        <ExplanationTxt>YALE NEW HAVEN HEALTH SERVICES CORPORATION AND HARTFORD HEALTHCARE CORPORATION SHALL HAVE THE RIGHT TO ELECT THE FILING ORGANIZATION'S MANAGEMENT COMMITTEE MEMBERS IN ACCORDANCE WITH THE OPERATING AGREEMENT.</ExplanationTxt>
      </SupplementalInformationDetail>
      <SupplementalInformationDetail>
        <FormAndLineReferenceDesc>FORM 990, PART VI, SECTION A, LINE 7B</FormAndLineReferenceDesc>
        <ExplanationTxt>THE MANAGEMENT COMMITTEE MEMBERS SHALL CONSULT REGULARLY WITH APPROPRIATE OFFICIALS OF YALE NEW HAVEN HEALTH SERVICES CORPORATION AND HARTFORD HEALTHCARE CORPORATION TO INSURE THAT ALL OF THE ACTIVITIES OF THIS CORPORATION ARE CONSISTENT WITH THE CHARTER, BYLAWS, RULES, REGULATIONS AND POLICIES OF YALE NEW HAVEN HEALTH SERVICES CORPORATION AND HARTFORD HEALTHCARE CORPORATION.</ExplanationTxt>
      </SupplementalInformationDetail>
      <SupplementalInformationDetail>
        <FormAndLineReferenceDesc>FORM 990, PART VI, SECTION B, LINE 11B</FormAndLineReferenceDesc>
        <ExplanationTxt>THE FORM 990 TAX RETURN AND ATTACHED SCHEDULES WERE PREPARED BY EMPLOYEES OF YALE NEW HAVEN HEALTH SERVICES CORPORATION'S TAX DEPARTMENT. THE RETURN IS INITIALLY REVIEWED BY THE EXECUTIVE DIRECTOR OF CORPORATE FINANCE. SUBSEQUENTLY IT IS SENT TO KPMG LLP FOR THEIR INITIAL REVIEW. AFTER ALL COMMENTS FROM THE ABOVE GROUPS ARE CLEARED, THE RETURN IS THEN REVIEWED BY HARTFORD HEALTHCARE CORPORATION'S TAX DEPARTMENT. UPON THEIR REVIEW, A FINAL VERSION OF THE RETURN IS SENT BACK TO KPMG LLP FOR FINAL REVIEW. PRIOR TO FILING THE ORGANIZATION MADE AVAILABLE A COMPLETE COPY OF THE RETURN TO THE MANAGEMENT COMMITTEE.</ExplanationTxt>
      </SupplementalInformationDetail>
      <SupplementalInformationDetail>
        <FormAndLineReferenceDesc>FORM 990, PART VI, SECTION B, LINE 12</FormAndLineReferenceDesc>
        <ExplanationTxt>CONNECTICUT PROTON THERAPY CENTER, LLC, WHILE THE ORGANIZATION DID NOT ADOPT A WRITTEN CONFLICT OF INTEREST POLICY, WHISTLEBLOWER POLICY OR DOCUMENT RETENTION AND DESTRUCTION POLICY IN THE TAX PERIOD ENDING 9/30/2024, THE ORGANIZATION HAS SINCE ADOPTED THESE POLICIES ON 9/19/25 WITHIN THE TAX PERIOD ENDING 9/30/2025.</ExplanationTxt>
      </SupplementalInformationDetail>
      <SupplementalInformationDetail>
        <FormAndLineReferenceDesc>FORM 990, PART VI, SECTION C, LINE 19</FormAndLineReferenceDesc>
        <ExplanationTxt>COPIES OF ALL DOCUMENTS ARE AVAILABLE TO THE PUBLIC UPON REQUEST.</ExplanationTxt>
      </SupplementalInformationDetail>
      <SupplementalInformationDetail>
        <FormAndLineReferenceDesc>FORM 990, PART IX, LINE 11G</FormAndLineReferenceDesc>
        <ExplanationTxt>PROFESSIONAL FEES: PROGRAM SERVICE EXPENSES 197,907. MANAGEMENT AND GENERAL EXPENSES 0. FUNDRAISING EXPENSES 0. TOTAL EXPENSES 197,907.</ExplanationTxt>
      </SupplementalInformationDetail>
      <SupplementalInformationDetail>
        <FormAndLineReferenceDesc>FORM 990, PART X</FormAndLineReferenceDesc>
        <ExplanationTxt>CONNECTICUT PROTON THERAPY CENTER, LLC, CONVERTED FROM A PARTNERSHIP TO A TAX-EXEMPT ORGANIZATION EFFECTIVE 9/4/2024. THE BALANCES SHOWN ON THE BEGINNING BALANCE SHEET FOR THIS FILING REMAINED WITHIN THE ORGANIZATION AS IT TRANSITIONED FROM A PARTNERSHIP TO A TAX-EXEMPT ORGANIZATION.</ExplanationTxt>
      </SupplementalInformationDetail>
    </IRS990ScheduleO>
  </ReturnData>
</Return>