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

    <schemaVersion>X0303</schemaVersion>

    <documentType>4</documentType>

    <periodOfReport>2010-10-11</periodOfReport>

    <notSubjectToSection16>0</notSubjectToSection16>

    <issuer>
        <issuerCik>0001207074</issuerCik>
        <issuerName>VIRTUSA CORP</issuerName>
        <issuerTradingSymbol>VRTU</issuerTradingSymbol>
    </issuer>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001395240</rptOwnerCik>
            <rptOwnerName>Armony Izhar</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>1000 WINTER STREET</rptOwnerStreet1>
            <rptOwnerStreet2>SUITE 3300</rptOwnerStreet2>
            <rptOwnerCity>WALTHAM</rptOwnerCity>
            <rptOwnerState>MA</rptOwnerState>
            <rptOwnerZipCode>02451</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</value>
            </securityTitle>
            <transactionDate>
                <value>2010-10-11</value>
            </transactionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>S</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
            </transactionCoding>
            <transactionTimeliness>
                <value></value>
            </transactionTimeliness>
            <transactionAmounts>
                <transactionShares>
                    <value>69111</value>
                    <footnoteId id="F1"/>
                    <footnoteId id="F2"/>
                </transactionShares>
                <transactionPricePerShare>
                    <value>10.3109</value>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>D</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>100000</value>
                    <footnoteId id="F2"/>
                    <footnoteId id="F3"/>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>I</value>
                </directOrIndirectOwnership>
                <natureOfOwnership>
                    <value>See Footnotes</value>
                    <footnoteId id="F2"/>
                    <footnoteId id="F4"/>
                </natureOfOwnership>
            </ownershipNature>
        </nonDerivativeTransaction>
    </nonDerivativeTable>

    <footnotes>
        <footnote id="F1">Represents 67,061 shares sold by Charles River Partnership XI, LP (&quot;CRP XI&quot;), 1,694 shares sold by Charles River Friends XI-A, LP (&quot;CRF XI-A&quot;), and 356 shares sold by Charles River Friends XI-B, LP (&quot;CRF XI-B&quot; and, together with CRP XI and CRF XI-A, the &quot;Partnerships&quot;).</footnote>
        <footnote id="F2">Izhar Armony disclaims beneficial ownership of the securities reported herein held by the Partnerships except to the extent of his pecuniary interest in each applicable Partnership, if any. The filing of this statement by Izhar Armony shall not be deemed an admission that he is, for purposes of Section 16 of the Securities Exchange Act of 1934 or otherwise, the beneficial owner of any equity securities covered by this statement.  Mr. Armony does not exercise investment or voting control over any of the Partnerships.</footnote>
        <footnote id="F3">Represents 97,039 shares held by CRP XI, 2,449 shares held by CRF XI-A, and 512 shares held by CRF XI-B.</footnote>
        <footnote id="F4">Charles River XI GP, LLC (&quot;CR XI GP LLC&quot;) is the General Partner of Charles River XI GP, LP (&quot;CR XI GP LP&quot;).  CR XI GP LP is in turn the General Partner of CRP XI.  CR XI GP LLC is also the General Partner of CRF XI-A and CRF XI-B.  The Partnerships form a &quot;group&quot; for purposes of Section 13(d) of the Securities Exchange Act of 1934.  Each of Izhar Armony, Christopher Baldwin, Richard M. Burnes, Jr., Ted R. Dintesmith, Bruce I. Sachs, William P. Tai, and Michael J. Zak is a managing member of CR XI GP, LLC.  Accordingly, each of CR XI GP LP, CR XI GP LLC, and Messrs. Armony, Baldwin, Burnes, Dintersmith, Sachs, Tai, and Zak (collectively, the &quot;Management Persons&quot;) may be deemed to beneficially own the securities owned by the Partnerships.</footnote>
    </footnotes>

    <ownerSignature>
        <signatureName>John A. Genest, Attorney-in-Fact for Izhar Armony</signatureName>
        <signatureDate>2010-10-13</signatureDate>
    </ownerSignature>
</ownershipDocument>
