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

    <schemaVersion>X0306</schemaVersion>

    <documentType>4/A</documentType>

    <periodOfReport>2019-02-05</periodOfReport>

    <dateOfOriginalSubmission>2019-02-07</dateOfOriginalSubmission>

    <notSubjectToSection16>0</notSubjectToSection16>

    <issuer>
        <issuerCik>0001584207</issuerCik>
        <issuerName>OneMain Holdings, Inc.</issuerName>
        <issuerTradingSymbol>OMF</issuerTradingSymbol>
    </issuer>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001495547</rptOwnerCik>
            <rptOwnerName>PARKER SCOTT T</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>C/O ONEMAIN HOLDINGS, INC.</rptOwnerStreet1>
            <rptOwnerStreet2>601 N.W. SECOND STREET</rptOwnerStreet2>
            <rptOwnerCity>EVANSVILLE</rptOwnerCity>
            <rptOwnerState>IN</rptOwnerState>
            <rptOwnerZipCode>47708</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>0</isDirector>
            <isOfficer>1</isOfficer>
            <isTenPercentOwner>0</isTenPercentOwner>
            <isOther>0</isOther>
            <officerTitle>EVP and CFO</officerTitle>
        </reportingOwnerRelationship>
    </reportingOwner>

    <nonDerivativeTable>
        <nonDerivativeTransaction>
            <securityTitle>
                <value>Common Stock, par value $0.01 per share</value>
            </securityTitle>
            <transactionDate>
                <value>2019-02-05</value>
            </transactionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>A</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
            </transactionCoding>
            <transactionTimeliness>
                <value></value>
            </transactionTimeliness>
            <transactionAmounts>
                <transactionShares>
                    <value>46309</value>
                    <footnoteId id="F1"/>
                </transactionShares>
                <transactionPricePerShare>
                    <value>0</value>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>A</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>338946</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
            </ownershipNature>
        </nonDerivativeTransaction>
    </nonDerivativeTable>

    <footnotes>
        <footnote id="F1">Consists of employee restricted stock units granted under the OneMain Holdings, Inc. Amended and Restated 2013 Omnibus Incentive Plan. The  restricted stock units vest as follows: 33.3% on each of February 20, 2019, and February 20, 2020, and 33.4% on February 19, 2021, subject to the reporting person's continued employment through the specified vesting date.</footnote>
    </footnotes>

    <remarks>The purpose of this amendment is to correct the number of employee restricted stock units granted under the OneMain Holdings, Inc. Amended and Restated 2013 Omnibus Incentive Plan as originally reported on Table I, line 1.</remarks>

    <ownerSignature>
        <signatureName>/s/ Jack R. Erkilla attorney-in-fact for Scott T. Parker</signatureName>
        <signatureDate>2019-02-22</signatureDate>
    </ownerSignature>
</ownershipDocument>
