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

    <schemaVersion>X0306</schemaVersion>

    <documentType>4</documentType>

    <periodOfReport>2015-01-02</periodOfReport>

    <notSubjectToSection16>0</notSubjectToSection16>

    <issuer>
        <issuerCik>0001085621</issuerCik>
        <issuerName>Actua Corp</issuerName>
        <issuerTradingSymbol>ACTA</issuerTradingSymbol>
    </issuer>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001493024</rptOwnerCik>
            <rptOwnerName>Miller Peter K</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>C/O ACTUA CORPORATION</rptOwnerStreet1>
            <rptOwnerStreet2>555 E. LANCASTER AVENUE, SUITE 640</rptOwnerStreet2>
            <rptOwnerCity>RADNOR</rptOwnerCity>
            <rptOwnerState>PA</rptOwnerState>
            <rptOwnerZipCode>19087</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>1</isDirector>
            <isOfficer>0</isOfficer>
            <isTenPercentOwner>0</isTenPercentOwner>
            <isOther>0</isOther>
        </reportingOwnerRelationship>
    </reportingOwner>

    <nonDerivativeTable>
        <nonDerivativeTransaction>
            <securityTitle>
                <value>Common Stock, par value $.001 per share</value>
            </securityTitle>
            <transactionDate>
                <value>2015-01-02</value>
            </transactionDate>
            <deemedExecutionDate></deemedExecutionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>A</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
            </transactionCoding>
            <transactionTimeliness>
                <value></value>
            </transactionTimeliness>
            <transactionAmounts>
                <transactionShares>
                    <value>938</value>
                    <footnoteId id="F1"/>
                </transactionShares>
                <transactionPricePerShare>
                    <value>18.24</value>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>A</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>49496</value>
                    <footnoteId id="F2"/>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
            </ownershipNature>
        </nonDerivativeTransaction>
    </nonDerivativeTable>

    <footnotes>
        <footnote id="F1">This amount represents the right of the Reporting Person to receive an equivalent number of shares of Common Stock after the date of termination of his services as a director pursuant to the terms of the Actua Corporation Deferred Stock Unit Program.</footnote>
        <footnote id="F2">The amount includes:  (a) 16,1268 shares of Common Stock that the Reporting Person has the right to receive following the termination of his services as a director pursuant to the terms of the Actua Corporation Deferred Stock Unit Program, (b) 18,000 shares of Common Stock that the Reporting Person has a right to receive following the termination of his service or employment with the Company pursuant to the terms of the Actua Amended and Restated Non-Management Director Compensation Plan and (c) 12,000 restricted shares granted as an annual service grant pursuant to the Actua Amended and Restated Non-Management Director Compensation Plan.</footnote>
    </footnotes>

    <remarks></remarks>

    <ownerSignature>
        <signatureName>Luann M. Taiariol, as attorney-in-fact for Peter K. Miller</signatureName>
        <signatureDate>2015-01-05</signatureDate>
    </ownerSignature>
</ownershipDocument>
