<?xml version="1.0" encoding="utf-8"?>
<Return returnVersion="2023v4.0" xmlns="http://www.irs.gov/efile" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance">
  <ReturnHeader binaryAttachmentCnt="0">
    <ReturnTs>2024-03-12T16:50:28-07:00</ReturnTs>
    <TaxPeriodEndDt>2023-12-31</TaxPeriodEndDt>
    <PreparerFirmGrp>
      <PreparerFirmName>
        <BusinessNameLine1Txt>Mountain House Accounting LLC</BusinessNameLine1Txt>
      </PreparerFirmName>
      <PreparerUSAddress>
        <AddressLine1Txt>2401 S Marion St</AddressLine1Txt>
        <CityNm>Denvere</CityNm>
        <StateAbbreviationCd>CO</StateAbbreviationCd>
        <ZIPCd>80210</ZIPCd>
      </PreparerUSAddress>
    </PreparerFirmGrp>
    <ReturnTypeCd>990EZ</ReturnTypeCd>
    <TaxPeriodBeginDt>2023-01-01</TaxPeriodBeginDt>
    <Filer>
      <EIN>742295707</EIN>
      <BusinessName>
        <BusinessNameLine1Txt>ROCKY MOUNTAIN BRASSWORKS-A BRITISH BRASS BAND</BusinessNameLine1Txt>
      </BusinessName>
      <BusinessNameControlTxt>ROCK</BusinessNameControlTxt>
      <PhoneNum>3038186017</PhoneNum>
      <USAddress>
        <AddressLine1Txt>PO Box 61</AddressLine1Txt>
        <CityNm>Broomfield</CityNm>
        <StateAbbreviationCd>CO</StateAbbreviationCd>
        <ZIPCd>80038</ZIPCd>
      </USAddress>
    </Filer>
    <BusinessOfficerGrp>
      <PersonNm>John House</PersonNm>
      <PersonTitleTxt>Treasurer</PersonTitleTxt>
      <PhoneNum>3038186017</PhoneNum>
      <SignatureDt>2024-03-09</SignatureDt>
      <DiscussWithPaidPreparerInd>1</DiscussWithPaidPreparerInd>
    </BusinessOfficerGrp>
    <SigningOfficerGrp>
      <PersonFullName>
        <PersonFirstNm>John</PersonFirstNm>
        <PersonLastNm>House</PersonLastNm>
      </PersonFullName>
      <SSN>999009999</SSN>
    </SigningOfficerGrp>
    <IRSResponsiblePrtyInfoCurrInd>1</IRSResponsiblePrtyInfoCurrInd>
    <PreparerPersonGrp>
      <PreparerPersonNm>John House</PreparerPersonNm>
      <PTIN>P00036276</PTIN>
      <PhoneNum>3038186017</PhoneNum>
      <PreparationDt>2024-03-09</PreparationDt>
    </PreparerPersonGrp>
    <AdditionalFilerInformation>
      <TrustedCustomerGrp>
        <TrustedCustomerCd>1</TrustedCustomerCd>
        <OOBSecurityVerificationCd>11</OOBSecurityVerificationCd>
        <LastSubmissionRqrOOBCd>0</LastSubmissionRqrOOBCd>
        <AuthenticationAssuranceLevelCd>AAL2</AuthenticationAssuranceLevelCd>
      </TrustedCustomerGrp>
    </AdditionalFilerInformation>
    <TaxYr>2023</TaxYr>
    <BuildTS>2023-04-26 12:10:37Z</BuildTS>
  </ReturnHeader>
  <ReturnData documentCnt="4">
    <IRS990EZ documentId="R000001" referenceDocumentId="R000004" softwareId="23018249" softwareVersionNum="v1.00">
      <MethodOfAccountingAccrualInd>X</MethodOfAccountingAccrualInd>
      <WebsiteAddressTxt>www.rockymountainbrassworks.org</WebsiteAddressTxt>
      <Organization501c3Ind referenceDocumentId="R000002">X</Organization501c3Ind>
      <TypeOfOrganizationCorpInd>X</TypeOfOrganizationCorpInd>
      <GrossReceiptsAmt>27168</GrossReceiptsAmt>
      <InfoInScheduleOPartIInd>X</InfoInScheduleOPartIInd>
      <ContributionsGiftsGrantsEtcAmt>9069</ContributionsGiftsGrantsEtcAmt>
      <ProgramServiceRevenueAmt>14575</ProgramServiceRevenueAmt>
      <MembershipDuesAmt>1300</MembershipDuesAmt>
      <InvestmentIncomeAmt>176</InvestmentIncomeAmt>
      <SaleOfAssetsGrossAmt>0</SaleOfAssetsGrossAmt>
      <CostOrOtherBasisExpenseSaleAmt>0</CostOrOtherBasisExpenseSaleAmt>
      <GainOrLossFromSaleOfAssetsAmt>0</GainOrLossFromSaleOfAssetsAmt>
      <GamingGrossIncomeAmt>0</GamingGrossIncomeAmt>
      <FundraisingGrossIncomeAmt fndrsngEventContriPrevRptAmt="0">0</FundraisingGrossIncomeAmt>
      <SpecialEventsDirectExpensesAmt>0</SpecialEventsDirectExpensesAmt>
      <SpecialEventsNetIncomeLossAmt>0</SpecialEventsNetIncomeLossAmt>
      <GrossSalesOfInventoryAmt>0</GrossSalesOfInventoryAmt>
      <CostOfGoodsSoldAmt>0</CostOfGoodsSoldAmt>
      <GrossProfitLossSlsOfInvntryAmt>0</GrossProfitLossSlsOfInvntryAmt>
      <OtherRevenueTotalAmt>2048</OtherRevenueTotalAmt>
      <TotalRevenueAmt>27168</TotalRevenueAmt>
      <GrantsAndSimilarAmountsPaidAmt>0</GrantsAndSimilarAmountsPaidAmt>
      <BenefitsPaidToOrForMembersAmt>0</BenefitsPaidToOrForMembersAmt>
      <SalariesOtherCompEmplBnftAmt>0</SalariesOtherCompEmplBnftAmt>
      <FeesAndOtherPymtToIndCntrctAmt>7900</FeesAndOtherPymtToIndCntrctAmt>
      <OccupancyRentUtltsAndMaintAmt>10924</OccupancyRentUtltsAndMaintAmt>
      <PrintingPublicationsPostageAmt>38</PrintingPublicationsPostageAmt>
      <OtherExpensesTotalAmt>7458</OtherExpensesTotalAmt>
      <TotalExpensesAmt>26320</TotalExpensesAmt>
      <ExcessOrDeficitForYearAmt>848</ExcessOrDeficitForYearAmt>
      <NetAssetsOrFundBalancesBOYAmt>90275</NetAssetsOrFundBalancesBOYAmt>
      <OtherChangesInNetAssetsAmt>0</OtherChangesInNetAssetsAmt>
      <NetAssetsOrFundBalancesEOYAmt>91123</NetAssetsOrFundBalancesEOYAmt>
      <InfoInScheduleOPartIIInd>X</InfoInScheduleOPartIIInd>
      <CashSavingsAndInvestmentsGrp>
        <BOYAmt>40400</BOYAmt>
        <EOYAmt>41590</EOYAmt>
      </CashSavingsAndInvestmentsGrp>
      <LandAndBuildingsGrp>
        <BOYAmt>0</BOYAmt>
        <EOYAmt>0</EOYAmt>
      </LandAndBuildingsGrp>
      <OtherAssetsTotalDetail>
        <BOYAmt>50079</BOYAmt>
        <EOYAmt>49687</EOYAmt>
      </OtherAssetsTotalDetail>
      <Form990TotalAssetsGrp>
        <BOYAmt>90479</BOYAmt>
        <EOYAmt>91277</EOYAmt>
      </Form990TotalAssetsGrp>
      <SumOfTotalLiabilitiesGrp>
        <BOYAmt>204</BOYAmt>
        <EOYAmt>154</EOYAmt>
      </SumOfTotalLiabilitiesGrp>
      <NetAssetsOrFundBalancesGrp>
        <BOYAmt>90275</BOYAmt>
        <EOYAmt>91123</EOYAmt>
      </NetAssetsOrFundBalancesGrp>
      <PrimaryExemptPurposeTxt>To promote traditional British brass band music by performance and education.</PrimaryExemptPurposeTxt>
      <ProgramSrvcAccomplishmentGrp>
        <DescriptionProgramSrvcAccomTxt>Rocky Mountain Brassworks provided an opportunity for 30 brass and percussion musicians to rehearse and perform six ticketed concerts featuring traditional British brass band music, one free collaboration with a middle school band, and two free outdoor performances for a total of 1232 audience members.</DescriptionProgramSrvcAccomTxt>
        <GrantsAndAllocationsAmt>0</GrantsAndAllocationsAmt>
        <ProgramServiceExpensesAmt>18824</ProgramServiceExpensesAmt>
      </ProgramSrvcAccomplishmentGrp>
      <TotalProgramServiceExpensesAmt>18824</TotalProgramServiceExpensesAmt>
      <OfficerDirectorTrusteeEmplGrp>
        <PersonNm>Mike Lusby</PersonNm>
        <TitleTxt>Director</TitleTxt>
        <AverageHrsPerWkDevotedToPosRt>1</AverageHrsPerWkDevotedToPosRt>
        <CompensationAmt>0</CompensationAmt>
        <EmployeeBenefitProgramAmt>0</EmployeeBenefitProgramAmt>
        <ExpenseAccountOtherAllwncAmt>0</ExpenseAccountOtherAllwncAmt>
      </OfficerDirectorTrusteeEmplGrp>
      <OfficerDirectorTrusteeEmplGrp>
        <PersonNm>John House</PersonNm>
        <TitleTxt>Treasurer</TitleTxt>
        <AverageHrsPerWkDevotedToPosRt>3</AverageHrsPerWkDevotedToPosRt>
        <CompensationAmt>0</CompensationAmt>
        <EmployeeBenefitProgramAmt>0</EmployeeBenefitProgramAmt>
        <ExpenseAccountOtherAllwncAmt>0</ExpenseAccountOtherAllwncAmt>
      </OfficerDirectorTrusteeEmplGrp>
      <OfficerDirectorTrusteeEmplGrp>
        <PersonNm>Pamala Wolta</PersonNm>
        <TitleTxt>Vice President</TitleTxt>
        <AverageHrsPerWkDevotedToPosRt>3</AverageHrsPerWkDevotedToPosRt>
        <CompensationAmt>0</CompensationAmt>
        <EmployeeBenefitProgramAmt>0</EmployeeBenefitProgramAmt>
        <ExpenseAccountOtherAllwncAmt>0</ExpenseAccountOtherAllwncAmt>
      </OfficerDirectorTrusteeEmplGrp>
      <OfficerDirectorTrusteeEmplGrp>
        <PersonNm>George Villacres</PersonNm>
        <TitleTxt>Secretary</TitleTxt>
        <AverageHrsPerWkDevotedToPosRt>2</AverageHrsPerWkDevotedToPosRt>
        <CompensationAmt>0</CompensationAmt>
        <EmployeeBenefitProgramAmt>0</EmployeeBenefitProgramAmt>
        <ExpenseAccountOtherAllwncAmt>0</ExpenseAccountOtherAllwncAmt>
      </OfficerDirectorTrusteeEmplGrp>
      <OfficerDirectorTrusteeEmplGrp>
        <PersonNm>Ron Argotsinger</PersonNm>
        <TitleTxt>Director and Assistant Conductor</TitleTxt>
        <AverageHrsPerWkDevotedToPosRt>4</AverageHrsPerWkDevotedToPosRt>
        <CompensationAmt>4050</CompensationAmt>
        <EmployeeBenefitProgramAmt>0</EmployeeBenefitProgramAmt>
        <ExpenseAccountOtherAllwncAmt>0</ExpenseAccountOtherAllwncAmt>
      </OfficerDirectorTrusteeEmplGrp>
      <OfficerDirectorTrusteeEmplGrp>
        <PersonNm>Dave MacLoughlin</PersonNm>
        <TitleTxt>President</TitleTxt>
        <AverageHrsPerWkDevotedToPosRt>2</AverageHrsPerWkDevotedToPosRt>
        <CompensationAmt>0</CompensationAmt>
        <EmployeeBenefitProgramAmt>0</EmployeeBenefitProgramAmt>
        <ExpenseAccountOtherAllwncAmt>0</ExpenseAccountOtherAllwncAmt>
      </OfficerDirectorTrusteeEmplGrp>
      <OfficerDirectorTrusteeEmplGrp>
        <PersonNm>John Ries</PersonNm>
        <TitleTxt>Director</TitleTxt>
        <AverageHrsPerWkDevotedToPosRt>1</AverageHrsPerWkDevotedToPosRt>
        <CompensationAmt>0</CompensationAmt>
        <EmployeeBenefitProgramAmt>0</EmployeeBenefitProgramAmt>
        <ExpenseAccountOtherAllwncAmt>0</ExpenseAccountOtherAllwncAmt>
      </OfficerDirectorTrusteeEmplGrp>
      <ActivitiesNotPreviouslyRptInd>0</ActivitiesNotPreviouslyRptInd>
      <ChgMadeToOrgnzngDocNotRptInd>0</ChgMadeToOrgnzngDocNotRptInd>
      <OrganizationHadUBIInd>0</OrganizationHadUBIInd>
      <SubjectToProxyTaxInd>0</SubjectToProxyTaxInd>
      <OrganizationDissolvedEtcInd>0</OrganizationDissolvedEtcInd>
      <DirectIndirectPltclExpendAmt>0</DirectIndirectPltclExpendAmt>
      <Form1120PolFiledInd>0</Form1120PolFiledInd>
      <MadeLoansToFromOfficersInd>0</MadeLoansToFromOfficersInd>
      <TaxImposedUnderIRC4911Amt>0</TaxImposedUnderIRC4911Amt>
      <TaxImposedUnderIRC4912Amt>0</TaxImposedUnderIRC4912Amt>
      <TaxImposedUnderIRC4955Amt>0</TaxImposedUnderIRC4955Amt>
      <EngagedInExcessBenefitTransInd>0</EngagedInExcessBenefitTransInd>
      <TaxImposedOnOrganizationMgrAmt>0</TaxImposedOnOrganizationMgrAmt>
      <TaxReimbursedByOrganizationAmt>0</TaxReimbursedByOrganizationAmt>
      <ProhibitedTaxShelterTransInd>0</ProhibitedTaxShelterTransInd>
      <BooksInCareOfDetail>
        <PersonNm>John House</PersonNm>
        <USAddress>
          <AddressLine1Txt>PO Box 61</AddressLine1Txt>
          <CityNm>Broomfield</CityNm>
          <StateAbbreviationCd>CO</StateAbbreviationCd>
          <ZIPCd>80038</ZIPCd>
        </USAddress>
        <PhoneNum>3038186017</PhoneNum>
      </BooksInCareOfDetail>
      <ForeignFinancialAccountInd>0</ForeignFinancialAccountInd>
      <ForeignOfficeInd>0</ForeignOfficeInd>
      <DonorAdvisedFndsInd>0</DonorAdvisedFndsInd>
      <OperateHospitalInd>0</OperateHospitalInd>
      <TanningServicesProvidedInd>0</TanningServicesProvidedInd>
      <RelatedOrganizationCtrlEntInd>0</RelatedOrganizationCtrlEntInd>
      <TransactionWithControlEntInd>0</TransactionWithControlEntInd>
      <PoliticalCampaignActyInd>0</PoliticalCampaignActyInd>
      <LobbyingActivitiesInd>0</LobbyingActivitiesInd>
      <SchoolOperatingInd>0</SchoolOperatingInd>
      <TrnsfrExmptNonChrtblRltdOrgInd>0</TrnsfrExmptNonChrtblRltdOrgInd>
      <PartVIOfCompOfHghstPdEmplTxt>NONE</PartVIOfCompOfHghstPdEmplTxt>
      <PartVIHghstPdCntrctProfSrvcTxt>NONE</PartVIHghstPdCntrctProfSrvcTxt>
      <FiledScheduleAInd>1</FiledScheduleAInd>
    </IRS990EZ>
    <IRS990ScheduleA documentId="R000002" softwareId="23018249" softwareVersionNum="v1.00">
      <PubliclySupportedOrg509a2Ind>X</PubliclySupportedOrg509a2Ind>
      <GiftsGrantsContrisRcvd509Grp>
        <CurrentTaxYearMinus4YearsAmt>16145</CurrentTaxYearMinus4YearsAmt>
        <CurrentTaxYearMinus3YearsAmt>9862</CurrentTaxYearMinus3YearsAmt>
        <CurrentTaxYearMinus2YearsAmt>11980</CurrentTaxYearMinus2YearsAmt>
        <CurrentTaxYearMinus1YearAmt>11689</CurrentTaxYearMinus1YearAmt>
        <CurrentTaxYearAmt>10369</CurrentTaxYearAmt>
        <TotalAmt>60045</TotalAmt>
      </GiftsGrantsContrisRcvd509Grp>
      <GrossReceiptsAdmissionsGrp>
        <CurrentTaxYearMinus4YearsAmt>14589</CurrentTaxYearMinus4YearsAmt>
        <CurrentTaxYearMinus3YearsAmt>2241</CurrentTaxYearMinus3YearsAmt>
        <CurrentTaxYearMinus2YearsAmt>4609</CurrentTaxYearMinus2YearsAmt>
        <CurrentTaxYearMinus1YearAmt>12209</CurrentTaxYearMinus1YearAmt>
        <CurrentTaxYearAmt>14575</CurrentTaxYearAmt>
        <TotalAmt>48223</TotalAmt>
      </GrossReceiptsAdmissionsGrp>
      <Total509Grp>
        <CurrentTaxYearMinus4YearsAmt>30734</CurrentTaxYearMinus4YearsAmt>
        <CurrentTaxYearMinus3YearsAmt>12103</CurrentTaxYearMinus3YearsAmt>
        <CurrentTaxYearMinus2YearsAmt>16589</CurrentTaxYearMinus2YearsAmt>
        <CurrentTaxYearMinus1YearAmt>23898</CurrentTaxYearMinus1YearAmt>
        <CurrentTaxYearAmt>24944</CurrentTaxYearAmt>
        <TotalAmt>108268</TotalAmt>
      </Total509Grp>
      <PublicSupportTotal509Amt>108268</PublicSupportTotal509Amt>
      <GrossInvestmentIncome509Grp>
        <CurrentTaxYearMinus4YearsAmt>21</CurrentTaxYearMinus4YearsAmt>
        <CurrentTaxYearMinus3YearsAmt>3</CurrentTaxYearMinus3YearsAmt>
        <CurrentTaxYearMinus2YearsAmt>2</CurrentTaxYearMinus2YearsAmt>
        <CurrentTaxYearMinus1YearAmt>6</CurrentTaxYearMinus1YearAmt>
        <CurrentTaxYearAmt>176</CurrentTaxYearAmt>
        <TotalAmt>208</TotalAmt>
      </GrossInvestmentIncome509Grp>
      <InvestmentIncomeAndUBTIGrp>
        <CurrentTaxYearMinus4YearsAmt>21</CurrentTaxYearMinus4YearsAmt>
        <CurrentTaxYearMinus3YearsAmt>3</CurrentTaxYearMinus3YearsAmt>
        <CurrentTaxYearMinus2YearsAmt>2</CurrentTaxYearMinus2YearsAmt>
        <CurrentTaxYearMinus1YearAmt>6</CurrentTaxYearMinus1YearAmt>
        <CurrentTaxYearAmt>176</CurrentTaxYearAmt>
        <TotalAmt>208</TotalAmt>
      </InvestmentIncomeAndUBTIGrp>
      <TotalSupportCalendarYearGrp>
        <CurrentTaxYearMinus4YearsAmt>30755</CurrentTaxYearMinus4YearsAmt>
        <CurrentTaxYearMinus3YearsAmt>12106</CurrentTaxYearMinus3YearsAmt>
        <CurrentTaxYearMinus2YearsAmt>16591</CurrentTaxYearMinus2YearsAmt>
        <CurrentTaxYearMinus1YearAmt>23904</CurrentTaxYearMinus1YearAmt>
        <CurrentTaxYearAmt>25120</CurrentTaxYearAmt>
        <TotalAmt>108476</TotalAmt>
      </TotalSupportCalendarYearGrp>
      <PublicSupportCY509Pct>0.99808</PublicSupportCY509Pct>
      <PublicSupportPY509Pct>0.99955</PublicSupportPY509Pct>
      <InvestmentIncomeCYPct>0.00192</InvestmentIncomeCYPct>
      <InvestmentIncomePYPct>0.00045</InvestmentIncomePYPct>
      <ThirtyThrPctSuprtTestsCY509Ind>X</ThirtyThrPctSuprtTestsCY509Ind>
    </IRS990ScheduleA>
    <IRS990ScheduleB documentId="R000003" softwareId="23018249" softwareVersionNum="v1.00">
      <ContributorInformationGrp>
        <ContributorNum>RESTRICTED</ContributorNum>
        <ContributorBusinessName>
          <BusinessNameLine1>RESTRICTED</BusinessNameLine1>
        </ContributorBusinessName>
        <ContributorUSAddress>
          <AddressLine1>RESTRICTED</AddressLine1>
          <AddressLine2>RESTRICTED</AddressLine2>
          <City>RESTRICTED</City>
          <State>RESTRICTED</State>
          <ZIPCode>RESTRICTED</ZIPCode>
        </ContributorUSAddress>
        <TotalContributionsAmt>RESTRICTED</TotalContributionsAmt>
      </ContributorInformationGrp>
    </IRS990ScheduleB>
    <IRS990ScheduleO documentId="R000004" softwareId="23018249" softwareVersionNum="v1.00">
      <SupplementalInformationDetail>
        <FormAndLineReferenceDesc>Form 990-EZ, Part I, Line 8</FormAndLineReferenceDesc>
        <ExplanationTxt>Description;Amount^Reclaimed revenue from concert in 2016;2048^Total;2048^</ExplanationTxt>
      </SupplementalInformationDetail>
      <SupplementalInformationDetail>
        <FormAndLineReferenceDesc>Form 990-EZ, Part I, Line 16</FormAndLineReferenceDesc>
        <ExplanationTxt>Description;Amount^Administrative Expenses;2072|Dues and Subscriptions;755|Repair and Maintenance;1863|Advertising and Marketing;1563|Program Supplies;338|Insurance;475|Depreciation;392^Total;7458^</ExplanationTxt>
      </SupplementalInformationDetail>
      <SupplementalInformationDetail>
        <FormAndLineReferenceDesc>Form 990-EZ, Part II, Line 24</FormAndLineReferenceDesc>
        <ExplanationTxt>Description;EOY Amount^Trailer;2742|Uniforms;2065|Music Library;21000|Musical Instruments;28300|Accumulated Depreciation Trailer Uniforms;-4420^Total;49687^</ExplanationTxt>
      </SupplementalInformationDetail>
      <SupplementalInformationDetail>
        <FormAndLineReferenceDesc>Form 990-EZ, Part II, Line 26</FormAndLineReferenceDesc>
        <ExplanationTxt>Description;EOY Amount^Deferred Revenue;154^Total;154^</ExplanationTxt>
      </SupplementalInformationDetail>
    </IRS990ScheduleO>
  </ReturnData>
</Return>
