<?xml version="1.0" encoding="UTF-8"?><edgarSubmission xmlns="http://www.sec.gov/edgar/ownership" xmlns:com="http://www.sec.gov/edgar/common">
  <headerData>
    <submissionType>144</submissionType>
    <filerInfo>
      <filer>
        <filerCredentials>
          <cik>0001675736</cik>
          <ccc>XXXXXXXX</ccc>
        </filerCredentials>
      </filer>
      <liveTestFlag>LIVE</liveTestFlag>



    </filerInfo>
  </headerData>
  <formData>
    <issuerInfo>
      <issuerCik>0000814547</issuerCik>
      <issuerName>FAIR ISAAC CORP</issuerName>
      <secFileNumber>001-11689</secFileNumber>
      <issuerAddress>
        <com:street1>5 WEST MENDENHALL</com:street1>
        <com:street2>SUITES 105</com:street2>
        <com:city>BOZEMAN</com:city>
        <com:stateOrCountry>MT</com:stateOrCountry>
        <com:zipCode>59715</com:zipCode>
      </issuerAddress>
      <issuerContactPhone>(406) 982-7276</issuerContactPhone>
      <nameOfPersonForWhoseAccountTheSecuritiesAreToBeSold>Bowers Thomas A.</nameOfPersonForWhoseAccountTheSecuritiesAreToBeSold>
      <relationshipsToIssuer>
        <relationshipToIssuer>Officer</relationshipToIssuer>
      </relationshipsToIssuer>
    </issuerInfo>
    <securitiesInformation>
      <securitiesClassTitle>Common</securitiesClassTitle>
      <brokerOrMarketmakerDetails>
        <name>Morgan Stanley Smith Barney LLC Executive Services</name>
        <address>
          <com:street1>200 W Civic Center Dr - 4th Floor</com:street1>
          <com:city>Sandy</com:city>
          <com:stateOrCountry>UT</com:stateOrCountry>
          <com:zipCode>84070</com:zipCode>
        </address>
      </brokerOrMarketmakerDetails>
      <noOfUnitsSold>2680</noOfUnitsSold>
      <aggregateMarketValue>6250537.20</aggregateMarketValue>
      <noOfUnitsOutstanding>24300000</noOfUnitsOutstanding>
      <approxSaleDate>11/11/2024</approxSaleDate>
      <securitiesExchangeName>NYSE</securitiesExchangeName>
    </securitiesInformation>
    <securitiesToBeSold>
      <securitiesClassTitle>COMMON</securitiesClassTitle>
      <acquiredDate>11/11/2024</acquiredDate>
      <natureOfAcquisitionTransaction>STOCK OPTION EXERCISE</natureOfAcquisitionTransaction>
      <nameOfPersonfromWhomAcquired>ISSUER</nameOfPersonfromWhomAcquired>
      <isGiftTransaction>N</isGiftTransaction>
      <amountOfSecuritiesAcquired>2680</amountOfSecuritiesAcquired>
      <paymentDate>11/11/2024</paymentDate>
      <natureOfPayment>COMPENSATION</natureOfPayment>
    </securitiesToBeSold>
    <nothingToReportFlagOnSecuritiesSoldInPast3Months>N</nothingToReportFlagOnSecuritiesSoldInPast3Months>
    <securitiesSoldInPast3Months>
      <sellerDetails>
        <name>THOMAS BOWERS</name>
        <address>
          <com:street1>5 WEST MENDENHALL</com:street1>
          <com:street2>SUITE 105</com:street2>
          <com:city>BOZEMAN</com:city>
          <com:stateOrCountry>MT</com:stateOrCountry>
          <com:zipCode>59715</com:zipCode>
        </address>
      </sellerDetails>
      <securitiesClassTitle>PERFORMANCE AND RESTRICTED STOCK</securitiesClassTitle>
      <saleDate>08/12/2024</saleDate>
      <amountOfSecuritiesSold>3000</amountOfSecuritiesSold>
      <grossProceeds>5145805.54</grossProceeds>
    </securitiesSoldInPast3Months>
    <noticeSignature>
      <noticeDate>11/11/2024</noticeDate>
      <signature>/s/ Thomas A. Bowers</signature>
    </noticeSignature>
  </formData>
</edgarSubmission>
