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

    <schemaVersion>X0303</schemaVersion>

    <documentType>4</documentType>

    <periodOfReport>2008-10-17</periodOfReport>

    <notSubjectToSection16>0</notSubjectToSection16>

    <issuer>
        <issuerCik>0000878088</issuerCik>
        <issuerName>PAR PHARMACEUTICAL COMPANIES, INC.</issuerName>
        <issuerTradingSymbol>PRX</issuerTradingSymbol>
    </issuer>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001055404</rptOwnerCik>
            <rptOwnerName>LEPORE PATRICK G</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>C/O PAR PHARMACEUTICAL COMPANIES INC.</rptOwnerStreet1>
            <rptOwnerStreet2>300 TICE BOULEVARD</rptOwnerStreet2>
            <rptOwnerCity>WOOCLIFF LAKE</rptOwnerCity>
            <rptOwnerState>NJ</rptOwnerState>
            <rptOwnerZipCode>07677</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>1</isDirector>
            <isOfficer>1</isOfficer>
            <isTenPercentOwner>0</isTenPercentOwner>
            <isOther>0</isOther>
            <officerTitle>Chairman, President &amp; CEO</officerTitle>
        </reportingOwnerRelationship>
    </reportingOwner>

    <nonDerivativeTable>
        <nonDerivativeTransaction>
            <securityTitle>
                <value>Common Stock</value>
            </securityTitle>
            <transactionDate>
                <value>2008-10-17</value>
            </transactionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>P</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
            </transactionCoding>
            <transactionTimeliness>
                <value></value>
            </transactionTimeliness>
            <transactionAmounts>
                <transactionShares>
                    <value>1400</value>
                </transactionShares>
                <transactionPricePerShare>
                    <value>10.5779</value>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>A</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>175430</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
            </ownershipNature>
        </nonDerivativeTransaction>
        <nonDerivativeTransaction>
            <securityTitle>
                <value>Common Stock</value>
            </securityTitle>
            <transactionDate>
                <value>2008-10-17</value>
            </transactionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>P</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
            </transactionCoding>
            <transactionTimeliness>
                <value></value>
            </transactionTimeliness>
            <transactionAmounts>
                <transactionShares>
                    <value>3600</value>
                </transactionShares>
                <transactionPricePerShare>
                    <value>10.58</value>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>A</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>179030</value>
                    <footnoteId id="F1"/>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
            </ownershipNature>
        </nonDerivativeTransaction>
        <nonDerivativeHolding>
            <securityTitle>
                <value>Common Stock</value>
            </securityTitle>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>15000</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>I</value>
                </directOrIndirectOwnership>
                <natureOfOwnership>
                    <value>By Limited Partnership</value>
                    <footnoteId id="F2"/>
                </natureOfOwnership>
            </ownershipNature>
        </nonDerivativeHolding>
        <nonDerivativeHolding>
            <securityTitle>
                <value>Common Stock</value>
            </securityTitle>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>15000</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>I</value>
                </directOrIndirectOwnership>
                <natureOfOwnership>
                    <value>By Trust</value>
                    <footnoteId id="F3"/>
                </natureOfOwnership>
            </ownershipNature>
        </nonDerivativeHolding>
    </nonDerivativeTable>

    <footnotes>
        <footnote id="F1">Includes (i) 27,893 shares of Common Stock, and (ii) 151,137 shares of Restricted Stock and Restricted Stock Units, held by Mr. LePore.</footnote>
        <footnote id="F2">The shares are held by Park Street Investors, L.P. (&quot;PSI&quot;), a Delaware limited partnership.  The General Partner of PSI is Park Street Investment Corporation (&quot;PSIC&quot;), a Delaware corporation, of which Mr. LePore and his spouse are officers and directors and together own a majority of the outstanding stock of PSIC.</footnote>
        <footnote id="F3">The shares are held by the Patrick LePore Revocable Trust of 2002, of which Mr. LePore is the Grantor, Trustee and beneficiary.</footnote>
    </footnotes>

    <remarks>LIMITED POWER OF ATTORNEY: KNOW ALL MEN BY THESE PRESENTS, that the undersigned does hereby constitute and appoint MARIAN E. GUSTAFSON with full power to act, as his/her true and lawful attorney-in-fact and agent, with full power of substitution and resubstitution, for him/her and in his/her name, place and stead, in any and all capacities, and to do any and all acts and things in his/her name and on his/her behalf, to execute any and all documents and instruments, which said attorney-in-fact may deem necessary or advisable to enable him/her to comply with the reporting requirements pursuant to Section 16 of the Securities Exchange Act of 1934, as amended, including but not limited to Form 4-Statement of Changes in Beneficial Ownership and Form 5-Annual Statement of Changes in Beneficial Ownership, relating to his/her ownership in Par Pharmaceutical Companies, Inc. (the &quot;Company&quot;) for the period October 1, 2008 through and including September 30, 2009; and to file the same, and all other documents in connection therewith, with the Securities and Exchange Commission, granting unto said attorney-in-fact and agent, full power and authority to do and perform each and every act and thing requisite and necessary to be done as fully to all intents and purposes as the undersigned might or could do in person, hereby ratifying and confirming all that the said attorney-in-fact and agent may lawfully do or cause to be done by virtue thereof. /s/ Patrick G. LePore  Dated: September 12, 2008</remarks>

    <ownerSignature>
        <signatureName>/s/ Marian E. Gustafson for Patrick G. LePore</signatureName>
        <signatureDate>2008-10-20</signatureDate>
    </ownerSignature>
</ownershipDocument>
