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      <SupplementalInformationDetail>
        <FormAndLineReferenceDesc>Part X, Line 2:</FormAndLineReferenceDesc>
        <ExplanationTxt>The trust established to hold the Plan's assets is intended to qualify pursuant to Section 501(c)(9) of the Internal Revenue Code, and accordingly, the Plan's net investment income is exempt from income taxes. The Plan has obtained an exemption letter dated July 30, 1999 from the Internal Revenue Service, and the Employer believes that the Plan, as amended, continues to qualify and to operate in accordance with the applicable requirements of the Internal Revenue Code. Therefore, no provision for income taxes has been inclued in the Plan's financial statements. Accounting principles generally accepted in the United States of America require plan management to evaluate tax positions taken by the Plan and recognize a tax liability (or asset) if the Plan has taken an uncertain tax position that more likely than not would not be sustained upon examination by the Internal Revenue Service. The Plan is subject to routine audits by taxing jurisdictions; however, there are currently no audits for any tax periods in progress.</ExplanationTxt>
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        <ExplanationTxt>First Interstate BancSystem, Inc's Benefits Committee has been delegated all management and fiduciary authority for the benefit plans of First Interstate BancSystem, Inc. There are 6 members of the Benefits Committee that oversee the health plan and they all have equal voting powers on matters.</ExplanationTxt>
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      <SupplementalInformationDetail>
        <FormAndLineReferenceDesc>Form 990, Part VI, Section A, line 2</FormAndLineReferenceDesc>
        <ExplanationTxt>Mike Cherwin, Kevin Riley, Marcy Mutch, Phil Gaglia, Jodi Delahunt Hubbell, and Rachel Turitto - business relationship.</ExplanationTxt>
      </SupplementalInformationDetail>
      <SupplementalInformationDetail>
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      <SupplementalInformationDetail>
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        <ExplanationTxt>The organization compensated First Interstate Wealth Management for services rendered as Trustee. A third party, Allegiance, files 1099's on behalf of First Interstate BancSystem Inc. Health Benefits Plan and Trust when required.</ExplanationTxt>
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      <SupplementalInformationDetail>
        <FormAndLineReferenceDesc>Form 990, Part V, Line 3A and 3B, Filing of Form 990-T</FormAndLineReferenceDesc>
        <ExplanationTxt>The organization is electing to set aside investment income for the purpose of payments for health benefits to its members. The set aside election has been made by filing Schedule G of Form 990-T, in addition to completing a Schedule in Support of Income Set Aside as attached to the 990-T.</ExplanationTxt>
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          <CityNm>Billings</CityNm>
          <StateAbbreviationCd>MT</StateAbbreviationCd>
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