<?xml version="1.0"?>
<ownershipDocument>

    <schemaVersion>X0508</schemaVersion>

    <documentType>4</documentType>

    <periodOfReport>2023-08-29</periodOfReport>

    <notSubjectToSection16>0</notSubjectToSection16>

    <issuer>
        <issuerCik>0001753162</issuerCik>
        <issuerName>Fathom Holdings Inc.</issuerName>
        <issuerTradingSymbol>FTHM</issuerTradingSymbol>
    </issuer>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001817237</rptOwnerCik>
            <rptOwnerName>Harley Joshua</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>C/O FATHOM HOLDINGS INC.</rptOwnerStreet1>
            <rptOwnerStreet2>2000 REGENCY PARKWAY DRIVE, SUITE 300</rptOwnerStreet2>
            <rptOwnerCity>CARY</rptOwnerCity>
            <rptOwnerState>NC</rptOwnerState>
            <rptOwnerZipCode>27518</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>1</isDirector>
            <isOfficer>1</isOfficer>
            <isTenPercentOwner>1</isTenPercentOwner>
            <isOther>0</isOther>
            <officerTitle>Chief Executive Officer</officerTitle>
        </reportingOwnerRelationship>
    </reportingOwner>

    <aff10b5One>0</aff10b5One>

    <nonDerivativeTable>
        <nonDerivativeTransaction>
            <securityTitle>
                <value>Common Stock</value>
            </securityTitle>
            <transactionDate>
                <value>2023-08-29</value>
            </transactionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>S</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
            </transactionCoding>
            <transactionTimeliness>
                <value></value>
            </transactionTimeliness>
            <transactionAmounts>
                <transactionShares>
                    <value>804</value>
                </transactionShares>
                <transactionPricePerShare>
                    <value>6.4</value>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>D</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>3156907</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                    <footnoteId id="F1"/>
                </directOrIndirectOwnership>
            </ownershipNature>
        </nonDerivativeTransaction>
        <nonDerivativeHolding>
            <securityTitle>
                <value>Common Stock</value>
            </securityTitle>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>2063032</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>I</value>
                    <footnoteId id="F2"/>
                </directOrIndirectOwnership>
                <natureOfOwnership>
                    <value>See Footnote (2)</value>
                </natureOfOwnership>
            </ownershipNature>
        </nonDerivativeHolding>
    </nonDerivativeTable>

    <footnotes>
        <footnote id="F1">Of these shares, 9,558 shares are restricted and vest in full on March 4, 2024, 4,426 shares are restricted and vest in full on July 1, 2024, 18,466 shares are restricted and vest in full on November 30, 2024, 29,616 shares are restricted and vest in full on March 31, 2024, 31,888 shares are restricted and vest in full on December 1, 2023, 47,170 shares are restricted and vest in full on December 1, 2023, 58,140 shares are restricted and vest in full on May 31, 2024, and 58,824 shares are restricted and vest in full on August 30, 2024.</footnote>
        <footnote id="F2">Includes an aggregate of 1,700,000 shares held by three trusts for which Mr. Harley serves as a trustee. Includes 363,032 shares held in a trust where an immediate family member serves as trustee.</footnote>
    </footnotes>

    <ownerSignature>
        <signatureName>/s/ Donald R. Reynolds, by Power of Attorney</signatureName>
        <signatureDate>2023-08-31</signatureDate>
    </ownerSignature>
</ownershipDocument>
