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

    <schemaVersion>X0306</schemaVersion>

    <documentType>4</documentType>

    <periodOfReport>2018-04-02</periodOfReport>

    <notSubjectToSection16>0</notSubjectToSection16>

    <issuer>
        <issuerCik>0001725255</issuerCik>
        <issuerName>DFB Healthcare Acquisitions Corp.</issuerName>
        <issuerTradingSymbol>DFBH</issuerTradingSymbol>
    </issuer>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001076341</rptOwnerCik>
            <rptOwnerName>BARASCH RICHARD A</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>C/O DFB HEALTHCARE ACQUISITIONS CORP.</rptOwnerStreet1>
            <rptOwnerStreet2>780 THIRD AVENUE, 37TH FLOOR</rptOwnerStreet2>
            <rptOwnerCity>NEW YORK</rptOwnerCity>
            <rptOwnerState>NY</rptOwnerState>
            <rptOwnerZipCode>10017</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>1</isDirector>
            <isOfficer>1</isOfficer>
            <isTenPercentOwner>1</isTenPercentOwner>
            <isOther>0</isOther>
            <officerTitle>President and CEO</officerTitle>
        </reportingOwnerRelationship>
    </reportingOwner>

    <nonDerivativeTable>
        <nonDerivativeTransaction>
            <securityTitle>
                <value>Common Stock</value>
            </securityTitle>
            <transactionDate>
                <value>2018-04-02</value>
            </transactionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>J</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
                <footnoteId id="F1"/>
            </transactionCoding>
            <transactionTimeliness>
                <value></value>
            </transactionTimeliness>
            <transactionAmounts>
                <transactionShares>
                    <value>921848</value>
                </transactionShares>
                <transactionPricePerShare>
                    <footnoteId id="F1"/>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>D</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>6045652</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>I</value>
                </directOrIndirectOwnership>
                <natureOfOwnership>
                    <value>See Footnote</value>
                    <footnoteId id="F2"/>
                </natureOfOwnership>
            </ownershipNature>
        </nonDerivativeTransaction>
    </nonDerivativeTable>

    <footnotes>
        <footnote id="F1">921,848 shares were forfeited to the Issuer at no cost in connection with the expiration of the underwriters' over-allotment option, as described in the Issuer's registration statement on Form S-1, as amended (File No. 333-222376).</footnote>
        <footnote id="F2">The shares are held directly by Deerfield/RAB Ventures, LLC and indirectly by Deerfield Private Design Fund IV, L.P., as member of Deerfield/RAB Ventures, LLC, Richard Barasch, as member and manager of Deerfield/RAB Ventures, LLC, and Steven Hochberg, as manager of Deerfield/RAB Ventures, LLC. Each of Deerfield Private Design Fund IV, L.P. and Messrs. Barasch and Hochberg disclaim beneficial ownership of the reported securities except to the extent of their pecuniary interest therein.</footnote>
    </footnotes>

    <ownerSignature>
        <signatureName>/s/ Alan I. Annex, Attorney-in-Fact</signatureName>
        <signatureDate>2018-04-03</signatureDate>
    </ownerSignature>
</ownershipDocument>
