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

    <schemaVersion>X0303</schemaVersion>

    <documentType>4/A</documentType>

    <periodOfReport>2008-08-22</periodOfReport>

    <dateOfOriginalSubmission>2008-08-26</dateOfOriginalSubmission>

    <notSubjectToSection16>0</notSubjectToSection16>

    <issuer>
        <issuerCik>0000940181</issuerCik>
        <issuerName>SKILLSOFT PUBLIC LIMITED CO</issuerName>
        <issuerTradingSymbol>SKIL</issuerTradingSymbol>
    </issuer>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001240189</rptOwnerCik>
            <rptOwnerName>MORAN CHARLES E</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>SKILLSOFT</rptOwnerStreet1>
            <rptOwnerStreet2>107 NORTHEASTERN BLVD</rptOwnerStreet2>
            <rptOwnerCity>NASHUA</rptOwnerCity>
            <rptOwnerState>NH</rptOwnerState>
            <rptOwnerZipCode>03062</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>1</isDirector>
            <isOfficer>1</isOfficer>
            <isTenPercentOwner>0</isTenPercentOwner>
            <isOther>0</isOther>
            <officerTitle>Chairman of the Board and CEO</officerTitle>
        </reportingOwnerRelationship>
    </reportingOwner>

    <nonDerivativeTable>
        <nonDerivativeTransaction>
            <securityTitle>
                <value>American Depositary Shares</value>
                <footnoteId id="F1"/>
            </securityTitle>
            <transactionDate>
                <value>2008-08-22</value>
            </transactionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>S</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
                <footnoteId id="F2"/>
            </transactionCoding>
            <transactionTimeliness>
                <value></value>
            </transactionTimeliness>
            <transactionAmounts>
                <transactionShares>
                    <value>37000</value>
                    <footnoteId id="F3"/>
                </transactionShares>
                <transactionPricePerShare>
                    <value>10.5936</value>
                    <footnoteId id="F4"/>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>D</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>102358</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>I</value>
                </directOrIndirectOwnership>
                <natureOfOwnership>
                    <value>See Footnote</value>
                    <footnoteId id="F5"/>
                </natureOfOwnership>
            </ownershipNature>
        </nonDerivativeTransaction>
        <nonDerivativeTransaction>
            <securityTitle>
                <value>American Depositary Shares</value>
                <footnoteId id="F1"/>
            </securityTitle>
            <transactionDate>
                <value>2008-08-22</value>
            </transactionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>S</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
                <footnoteId id="F6"/>
            </transactionCoding>
            <transactionTimeliness>
                <value></value>
            </transactionTimeliness>
            <transactionAmounts>
                <transactionShares>
                    <value>37000</value>
                    <footnoteId id="F3"/>
                </transactionShares>
                <transactionPricePerShare>
                    <value>10.5936</value>
                    <footnoteId id="F4"/>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>D</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>102358</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>I</value>
                </directOrIndirectOwnership>
                <natureOfOwnership>
                    <value>See Footnote</value>
                    <footnoteId id="F7"/>
                </natureOfOwnership>
            </ownershipNature>
        </nonDerivativeTransaction>
        <nonDerivativeTransaction>
            <securityTitle>
                <value>American Depositary Shares</value>
                <footnoteId id="F1"/>
            </securityTitle>
            <transactionDate>
                <value>2008-08-22</value>
            </transactionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>S</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
                <footnoteId id="F8"/>
            </transactionCoding>
            <transactionTimeliness>
                <value></value>
            </transactionTimeliness>
            <transactionAmounts>
                <transactionShares>
                    <value>37000</value>
                    <footnoteId id="F3"/>
                </transactionShares>
                <transactionPricePerShare>
                    <value>10.5936</value>
                    <footnoteId id="F4"/>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>D</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>102358</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>I</value>
                </directOrIndirectOwnership>
                <natureOfOwnership>
                    <value>See Footnote</value>
                    <footnoteId id="F9"/>
                </natureOfOwnership>
            </ownershipNature>
        </nonDerivativeTransaction>
        <nonDerivativeTransaction>
            <securityTitle>
                <value>American Depositary Shares</value>
                <footnoteId id="F1"/>
            </securityTitle>
            <transactionDate>
                <value>2008-08-22</value>
            </transactionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>S</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
                <footnoteId id="F10"/>
            </transactionCoding>
            <transactionTimeliness>
                <value></value>
            </transactionTimeliness>
            <transactionAmounts>
                <transactionShares>
                    <value>37000</value>
                    <footnoteId id="F3"/>
                </transactionShares>
                <transactionPricePerShare>
                    <value>10.5936</value>
                    <footnoteId id="F4"/>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>D</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>102358</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>I</value>
                </directOrIndirectOwnership>
                <natureOfOwnership>
                    <value>See Footnote</value>
                    <footnoteId id="F11"/>
                </natureOfOwnership>
            </ownershipNature>
        </nonDerivativeTransaction>
    </nonDerivativeTable>

    <footnotes>
        <footnote id="F1">American Depositary Shares evidenced by American Depositary Receipts, each of which represents one Ordinary Share of SkillSoft Public Limited Company, nominal value 0.11 (Euro) per Ordinary Share.</footnote>
        <footnote id="F2">Sale made pursuant to the Moran Children's Trust DTD 3-4-98 FBO Katie Moran Rule 10b5-1 Sales Plan adopted in July 2008.</footnote>
        <footnote id="F3">This amendment to Form 4 is filed to report the sale of an additional 2,000 shares on 8/22/2008, which shares inadvertently were omitted from the Form 4 filed on 8/26/2008.</footnote>
        <footnote id="F4">The price reported represents the weighted average price of the shares sold. Shares were sold at varying prices in the range of $10.55 - $10.80.  The Reporting Person hereby undertakes, upon request of the Staff of the U.S. Securities and Exchange Commission, the issuer or a security holder of the issuer, to provide full information regarding the number of shares sold at each separate price.</footnote>
        <footnote id="F5">Held by the Moran Children's Trust DTD 3-4-98 FBO Katie Moran, of which the Reporting Person's spouse is trustee.  The Reporting Person disclaims beneficial ownership of these securities to the extent to which such person does not have an actual pecuniary interest in these securities.</footnote>
        <footnote id="F6">Sale made pursuant to the Moran Children's Trust DTD 3-4-98 FBO Kelly Moran Rule 10b5-1 Sales Plan adopted in July 2008.</footnote>
        <footnote id="F7">Held by the Moran Children's Trust DTD 3-4-98 FBO Kelly Moran, of which the Reporting Person's spouse is trustee.  The Reporting Person disclaims beneficial ownership of these securities to the extent to which such person does not have an actual pecuniary interest in these securities.</footnote>
        <footnote id="F8">Sale made pursuant to the Moran Children's Trust DTD 3-4-98 FBO Kristin Moran Rule 10b5-1 Sales Plan adopted in July 2008.</footnote>
        <footnote id="F9">Held by the Moran Children's Trust DTD 3-4-98 FBO Kristin Moran, of which the Reporting Person's spouse is trustee.  The Reporting Person disclaims beneficial ownership of these securities to the extent to which such person does not have an actual pecuniary interest in these securities.</footnote>
        <footnote id="F10">Sale made pursuant to the Moran Children's Trust DTD 3-4-98 FBO Michael Moran Rule 10b5-1 Sales Plan adopted in July 2008.</footnote>
        <footnote id="F11">Held by the Moran Children's Trust DTD 3-4-98 FBO Michael Moran, of which the Reporting Person's spouse is trustee.  The Reporting Person disclaims beneficial ownership of these securities to the extent to which such person does not have an actual pecuniary interest in these securities.</footnote>
    </footnotes>

    <ownerSignature>
        <signatureName>/s/Greg Porto (for Charles E. Moran)</signatureName>
        <signatureDate>2008-08-29</signatureDate>
    </ownerSignature>
</ownershipDocument>
