<SEC-DOCUMENT>0001214659-15-000346.txt : 20150115
<SEC-HEADER>0001214659-15-000346.hdr.sgml : 20150115
<ACCEPTANCE-DATETIME>20150115191538
ACCESSION NUMBER:		0001214659-15-000346
CONFORMED SUBMISSION TYPE:	4/A
PUBLIC DOCUMENT COUNT:		1
CONFORMED PERIOD OF REPORT:	20141213
FILED AS OF DATE:		20150115
DATE AS OF CHANGE:		20150115

ISSUER:		

	COMPANY DATA:	
		COMPANY CONFORMED NAME:			FAIR ISAAC CORP
		CENTRAL INDEX KEY:			0000814547
		STANDARD INDUSTRIAL CLASSIFICATION:	SERVICES-BUSINESS SERVICES, NEC [7389]
		IRS NUMBER:				941499887
		STATE OF INCORPORATION:			DE
		FISCAL YEAR END:			0930

	BUSINESS ADDRESS:	
		STREET 1:		181 METRO DRIVE
		STREET 2:		SUITE 700
		CITY:			SAN JOSE
		STATE:			CA
		ZIP:			95110
		BUSINESS PHONE:		(408) 535-1500

	MAIL ADDRESS:	
		STREET 1:		181 METRO DRIVE
		STREET 2:		SUITE 700
		CITY:			SAN JOSE
		STATE:			CA
		ZIP:			95110

	FORMER COMPANY:	
		FORMER CONFORMED NAME:	FAIR ISAAC & COMPANY INC
		DATE OF NAME CHANGE:	19920703

REPORTING-OWNER:	

	OWNER DATA:	
		COMPANY CONFORMED NAME:			Pung Michael J
		CENTRAL INDEX KEY:			0001301887

	FILING VALUES:
		FORM TYPE:		4/A
		SEC ACT:		1934 Act
		SEC FILE NUMBER:	001-11689
		FILM NUMBER:		15531029

	MAIL ADDRESS:	
		STREET 1:		181 METRO DRIVE
		CITY:			SAN JOSE
		STATE:			CA
		ZIP:			95110
</SEC-HEADER>
<DOCUMENT>
<TYPE>4/A
<SEQUENCE>1
<FILENAME>marketforms-28479.xml
<DESCRIPTION>PRIMARY DOCUMENT
<TEXT>
<XML>
<?xml version="1.0"?>
<ownershipDocument>

    <schemaVersion>X0306</schemaVersion>

    <documentType>4/A</documentType>

    <periodOfReport>2014-12-13</periodOfReport>

    <dateOfOriginalSubmission>2014-12-16</dateOfOriginalSubmission>

    <issuer>
        <issuerCik>0000814547</issuerCik>
        <issuerName>FAIR ISAAC CORP</issuerName>
        <issuerTradingSymbol>FICO</issuerTradingSymbol>
    </issuer>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001301887</rptOwnerCik>
            <rptOwnerName>Pung Michael J</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>181 METRO DRIVE</rptOwnerStreet1>
            <rptOwnerStreet2></rptOwnerStreet2>
            <rptOwnerCity>SAN JOSE</rptOwnerCity>
            <rptOwnerState>CA</rptOwnerState>
            <rptOwnerZipCode>95110</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>false</isDirector>
            <isOfficer>true</isOfficer>
            <isTenPercentOwner>false</isTenPercentOwner>
            <isOther>false</isOther>
            <officerTitle>EVP &amp; CFO</officerTitle>
            <otherText></otherText>
        </reportingOwnerRelationship>
    </reportingOwner>

    <nonDerivativeTable>
        <nonDerivativeHolding>
            <securityTitle>
                <value>Common Stock</value>
            </securityTitle>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>62345</value>
                    <footnoteId id="F1"/>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>I</value>
                </directOrIndirectOwnership>
                <natureOfOwnership>
                    <value>Michael and Debora Pung 2014 Living Trust</value>
                </natureOfOwnership>
            </ownershipNature>
        </nonDerivativeHolding>
    </nonDerivativeTable>

    <derivativeTable></derivativeTable>

    <footnotes>
        <footnote id="F1">The reporting person's December 16, 2014 Form 4 filing inadvertently included his ESPP shares in his Trust's holdings and he is correcting this filing to exclude these shares from his Trust's holdings.  The ESPP shares disclosed as his direct holdings on the December 16, 2014 filing were properly reported.</footnote>
    </footnotes>

    <remarks></remarks>

    <ownerSignature>
        <signatureName>/s/Nancy E. Fraser, Attorney-in-fact</signatureName>
        <signatureDate>2015-01-15</signatureDate>
    </ownerSignature>
</ownershipDocument>
</XML>
</TEXT>
</DOCUMENT>
</SEC-DOCUMENT>
