<?xml version="1.0"?>

<ownershipDocument>

    <schemaVersion>X0201</schemaVersion>

    <documentType>4/A</documentType>

    <periodOfReport>2003-11-05</periodOfReport>

    <dateOfOriginalSubmission>2003-11-07</dateOfOriginalSubmission>

    <notSubjectToSection16>0</notSubjectToSection16>

    <issuer>
        <issuerCik>0000836267</issuerCik>
        <issuerName>R O C TAIWAN FUND</issuerName>
        <issuerTradingSymbol>ROC</issuerTradingSymbol>
    </issuer>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001190021</rptOwnerCik>
            <rptOwnerName>LAXEY PARTNERS LTD</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>STANLEY HOUSE</rptOwnerStreet1>
            <rptOwnerStreet2>7-9 MARKET HILL</rptOwnerStreet2>
            <rptOwnerCity>DOUGLAS, ISLE OF MAN</rptOwnerCity>
            <rptOwnerState>X0</rptOwnerState>
            <rptOwnerZipCode>IM1 2BF</rptOwnerZipCode>
            <rptOwnerStateDescription>UNITED KINGDOM</rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>0</isDirector>
            <isOfficer>0</isOfficer>
            <isTenPercentOwner>1</isTenPercentOwner>
            <isOther>0</isOther>
        </reportingOwnerRelationship>
    </reportingOwner>
    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001126078</rptOwnerCik>
            <rptOwnerName>VALUE CATALYST FUND LTD</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>PO BOX 309 UGLAND HOUSE</rptOwnerStreet1>
            <rptOwnerStreet2>SOUTH CHURCH STREET, GEORGE TOWN</rptOwnerStreet2>
            <rptOwnerCity>GRAND CAYMAN</rptOwnerCity>
            <rptOwnerState>E9</rptOwnerState>
            <rptOwnerZipCode></rptOwnerZipCode>
            <rptOwnerStateDescription>CAYMAN ISLANDS</rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>0</isDirector>
            <isOfficer>0</isOfficer>
            <isTenPercentOwner>1</isTenPercentOwner>
            <isOther>0</isOther>
        </reportingOwnerRelationship>
    </reportingOwner>
    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001190022</rptOwnerCik>
            <rptOwnerName>LP VALUE LTD</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>STANLEY HOUSE</rptOwnerStreet1>
            <rptOwnerStreet2>7-9 MARKET HILL</rptOwnerStreet2>
            <rptOwnerCity>DOUGLAS, ISLE OF MAN</rptOwnerCity>
            <rptOwnerState>X0</rptOwnerState>
            <rptOwnerZipCode>IM1 2BF</rptOwnerZipCode>
            <rptOwnerStateDescription>UNITED KINGDOM</rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>0</isDirector>
            <isOfficer>0</isOfficer>
            <isTenPercentOwner>1</isTenPercentOwner>
            <isOther>0</isOther>
        </reportingOwnerRelationship>
    </reportingOwner>
    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001255881</rptOwnerCik>
            <rptOwnerName>LAXEY INVESTORS LP</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>SAMUEL HARRIS HOUSE</rptOwnerStreet1>
            <rptOwnerStreet2>ST GEORGE'S STREET</rptOwnerStreet2>
            <rptOwnerCity>DOUGLAS, ISLE OF MAN</rptOwnerCity>
            <rptOwnerState>X0</rptOwnerState>
            <rptOwnerZipCode>IM99 1EZ</rptOwnerZipCode>
            <rptOwnerStateDescription>UNITED KINGDOM</rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>0</isDirector>
            <isOfficer>0</isOfficer>
            <isTenPercentOwner>1</isTenPercentOwner>
            <isOther>0</isOther>
        </reportingOwnerRelationship>
    </reportingOwner>
    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001255864</rptOwnerCik>
            <rptOwnerName>LAXEY INVESTORS LTD</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>AKARA BUILDING, 24 DE CASTRO STREET</rptOwnerStreet1>
            <rptOwnerStreet2>WICKHAMS CAY I</rptOwnerStreet2>
            <rptOwnerCity>ROAD TOWN, TORTOLA</rptOwnerCity>
            <rptOwnerState>D8</rptOwnerState>
            <rptOwnerZipCode></rptOwnerZipCode>
            <rptOwnerStateDescription>VIRGIN ISLANDS, BRITISH</rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>0</isDirector>
            <isOfficer>0</isOfficer>
            <isTenPercentOwner>1</isTenPercentOwner>
            <isOther>0</isOther>
        </reportingOwnerRelationship>
    </reportingOwner>
    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001255871</rptOwnerCik>
            <rptOwnerName>LAXEY UNIVERSAL VALUE LP</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>SAMUEL HARRIS HOUSE</rptOwnerStreet1>
            <rptOwnerStreet2>ST GEORGE'S STREET</rptOwnerStreet2>
            <rptOwnerCity>DOUGLAS, ISLE OF MAN</rptOwnerCity>
            <rptOwnerState>X0</rptOwnerState>
            <rptOwnerZipCode>IM99 1EZ</rptOwnerZipCode>
            <rptOwnerStateDescription>UNITED KINGDOM</rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>0</isDirector>
            <isOfficer>0</isOfficer>
            <isTenPercentOwner>1</isTenPercentOwner>
            <isOther>0</isOther>
        </reportingOwnerRelationship>
    </reportingOwner>
    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001255869</rptOwnerCik>
            <rptOwnerName>KINGSNORTH COLIN</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>STANLEY HOUSE</rptOwnerStreet1>
            <rptOwnerStreet2>7-9 MARKET HILL</rptOwnerStreet2>
            <rptOwnerCity>DOUGLAS, ISLE OF MAN</rptOwnerCity>
            <rptOwnerState>X0</rptOwnerState>
            <rptOwnerZipCode>IM1 2BF</rptOwnerZipCode>
            <rptOwnerStateDescription>UNITED KINGDOM</rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>0</isDirector>
            <isOfficer>0</isOfficer>
            <isTenPercentOwner>1</isTenPercentOwner>
            <isOther>0</isOther>
        </reportingOwnerRelationship>
    </reportingOwner>
    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001255866</rptOwnerCik>
            <rptOwnerName>PEGGE ANDREW</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>STANLEY HOUSE</rptOwnerStreet1>
            <rptOwnerStreet2>7-9 MARKET HILL</rptOwnerStreet2>
            <rptOwnerCity>DOUGLAS, ISLE OF MAN</rptOwnerCity>
            <rptOwnerState>X0</rptOwnerState>
            <rptOwnerZipCode>IM1 2BF</rptOwnerZipCode>
            <rptOwnerStateDescription>UNITED KINGDOM</rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>0</isDirector>
            <isOfficer>0</isOfficer>
            <isTenPercentOwner>1</isTenPercentOwner>
            <isOther>0</isOther>
        </reportingOwnerRelationship>
    </reportingOwner>

    <nonDerivativeTable>

        <nonDerivativeTransaction>
            <securityTitle>
                <value>Common Stock</value>
            </securityTitle>
            <transactionDate>
                <value>2003-11-05</value>
            </transactionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>P</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
            </transactionCoding>
            <transactionTimeliness>
                <value></value>
            </transactionTimeliness>
            <transactionAmounts>
                <transactionShares>
                    <value>63200</value>
                    <footnoteId id="F1"/>
                </transactionShares>
                <transactionPricePerShare>
                    <value>4.73</value>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>A</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>4704856</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>I</value>
                </directOrIndirectOwnership>
                <natureOfOwnership>
                    <value>See footnote</value>
                    <footnoteId id="F2"/>
                </natureOfOwnership>
            </ownershipNature>
        </nonDerivativeTransaction>

        <nonDerivativeTransaction>
            <securityTitle>
                <value>Common Stock</value>
            </securityTitle>
            <transactionDate>
                <value>2003-11-06</value>
            </transactionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>P</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
            </transactionCoding>
            <transactionTimeliness>
                <value></value>
            </transactionTimeliness>
            <transactionAmounts>
                <transactionShares>
                    <value>630000</value>
                    <footnoteId id="F1"/>
                </transactionShares>
                <transactionPricePerShare>
                    <value>4.654</value>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>A</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>5334856</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>I</value>
                </directOrIndirectOwnership>
                <natureOfOwnership>
                    <value>See footnote</value>
                    <footnoteId id="F3"/>
                </natureOfOwnership>
            </ownershipNature>
        </nonDerivativeTransaction>

    </nonDerivativeTable>

    <footnotes>
        <footnote id="F1">These shares are owned directly by LIL and indirectly by (i) Laxey as the investment manager of LIL, (ii) Kingsnorth pursuant to Kingsnorth's ownership interest of one half of the outstanding equity of Laxey, and (iii) Pegge pursuant to Pegge's ownership interest of one half of the outstanding equity of Laxey.  No other member of the &quot;group&quot; had a pecuniary interest in such shares under current Exchange Act rules and regulations.</footnote>
        <footnote id="F2">On November 5, 2003, Laxey owned 1,000 shares directly and 4,703,856 shares indirectly as the investment manager of each of Catalyst, LPV, LLP, LIL and LUV ( subject to the overall control of each entity's board of directors or general partner (as applicable)) and as the investment manager of various third party discretionary accounts managed for unaffiliated entities.  Kingsnorth owned indirectly all such shares pursuant to Kingsnorth's ownership interest of one half of the outstanding equity of Laxey and  Pegge owned indirectly all such shares pursuant to Pegge's ownership interest of one half of the outstanding equity of Laxey.</footnote>
        <footnote id="F3">On November 6, 2003, Laxey owned 1,000 shares directly and 5,333,856 shares indirectly as the investment manager of each of Catalyst, LPV, LLP, LIL and LUV (subject to the overall control of each entity's board of directors or general partner (as applicable)) and as the investment manager of various third party discretionary accounts managed for unaffiliated entities.  Kingsnorth owned indirectly all such shares pursuant to Kingsnorth's ownership interest of one half of the outstanding equity of Laxey and  Pegge owned indirectly all such shares pursuant to Pegge's ownership interest of one half of the outstanding equity of Laxey.</footnote>
    </footnotes>

    <remarks>This statement is being filed jointly by (i) Laxey Partners Limited, an Isle of Man company (&quot;Laxey&quot;), (ii) The Value Catalyst Fund Limited, a Cayman Islands company (&quot;Catalyst&quot;), (iii) LP Value Limited, a British Virgin Islands company (&quot;LPV&quot;), (iv) Laxey Investors L.P., a Delaware limited partnership (&quot;LLP&quot;), (v) Laxey Investors Limited, a British Virgin Islands company (&quot;LIL&quot;), (vi) Laxey Universal Value, LP, a Delaware limited partnership (&quot;LUV&quot;), (vii) Colin Kingsnorth, a British citizen (&quot;Kingsnorth&quot;) and (viii) Andrew Pegge, a British citizen (&quot;Pegge&quot;).  Laxey, together with Catalyst, LPV, LLP, LIL, LUV, Kingsnorth and Pegge, may be deemed to constitute a &quot;group&quot; for purposes of Section 13(d) promulgated under the Exchange Act.</remarks>

    <ownerSignature>
        <signatureName>/s/ Chris Bruce, Laxey Partners Limited</signatureName>
        <signatureDate>2003-11-13</signatureDate>
    </ownerSignature>
    <ownerSignature>
        <signatureName>/s/ Elizabeth Tunsell, The Value Catalyst Fund Limited</signatureName>
        <signatureDate>2003-11-13</signatureDate>
    </ownerSignature>
    <ownerSignature>
        <signatureName>/s/ Chris Bruce, LP Value Limited</signatureName>
        <signatureDate>2003-11-13</signatureDate>
    </ownerSignature>
    <ownerSignature>
        <signatureName>/s/ Chris Bruce, Laxey Investors L.P.</signatureName>
        <signatureDate>2003-11-13</signatureDate>
    </ownerSignature>
    <ownerSignature>
        <signatureName>/s/ Elizabeth Tunsell, Laxey Investors Limited</signatureName>
        <signatureDate>2003-11-13</signatureDate>
    </ownerSignature>
    <ownerSignature>
        <signatureName>/s/ Chris Bruce, Laxey Universal Value, LP</signatureName>
        <signatureDate>2003-11-13</signatureDate>
    </ownerSignature>
    <ownerSignature>
        <signatureName>/s/ Colin Kingsnorth</signatureName>
        <signatureDate>2003-11-13</signatureDate>
    </ownerSignature>
    <ownerSignature>
        <signatureName>/s/ Andrew Pegge</signatureName>
        <signatureDate>2003-11-13</signatureDate>
    </ownerSignature>

</ownershipDocument>

