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

    <schemaVersion>X0202</schemaVersion>

    <documentType>4</documentType>

    <periodOfReport>2006-07-31</periodOfReport>

    <notSubjectToSection16>0</notSubjectToSection16>

    <issuer>
        <issuerCik>0001022408</issuerCik>
        <issuerName>EPLUS INC</issuerName>
        <issuerTradingSymbol>PLUS</issuerTradingSymbol>
    </issuer>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001019966</rptOwnerCik>
            <rptOwnerName>HOVDE STEVEN D</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>1110 LAKE COOK ROAD</rptOwnerStreet1>
            <rptOwnerStreet2>SUITE 165</rptOwnerStreet2>
            <rptOwnerCity>BUFFALO GROVE</rptOwnerCity>
            <rptOwnerState>IL</rptOwnerState>
            <rptOwnerZipCode>60089</rptOwnerZipCode>
            <rptOwnerStateDescription></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>2006-07-31</value>
            </transactionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>P</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
            </transactionCoding>
            <transactionTimeliness>
                <value></value>
            </transactionTimeliness>
            <transactionAmounts>
                <transactionShares>
                    <value>5700</value>
                </transactionShares>
                <transactionPricePerShare>
                    <value>9.07</value>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>A</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>1215327</value>
                    <footnoteId id="F1"/>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>I</value>
                    <footnoteId id="F2"/>
                </directOrIndirectOwnership>
                <natureOfOwnership>
                    <value>SEE FOOTNOTE 2</value>
                    <footnoteId id="F2"/>
                </natureOfOwnership>
            </ownershipNature>
        </nonDerivativeTransaction>
        <nonDerivativeTransaction>
            <securityTitle>
                <value>COMMON STOCK</value>
            </securityTitle>
            <transactionDate>
                <value>2006-08-01</value>
            </transactionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>P</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
            </transactionCoding>
            <transactionTimeliness>
                <value></value>
            </transactionTimeliness>
            <transactionAmounts>
                <transactionShares>
                    <value>2040</value>
                </transactionShares>
                <transactionPricePerShare>
                    <value>9.17</value>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>A</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>1215327</value>
                    <footnoteId id="F1"/>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>I</value>
                    <footnoteId id="F2"/>
                </directOrIndirectOwnership>
                <natureOfOwnership>
                    <value>SEE FOOTNOTE 2</value>
                    <footnoteId id="F2"/>
                </natureOfOwnership>
            </ownershipNature>
        </nonDerivativeTransaction>
    </nonDerivativeTable>

    <footnotes>
        <footnote id="F1">As of the date hereof, including the transaction reported herein, Steven D. Hovde is the beneficial owner (within the meaning of Section 16 of the Securities Exchange Act of 1934, as amended) of 1,215,327 shares of common stock of EPlus, Inc. (the Shares).  The transactions reported herein reflect two purchase of the Shares by Financial Institution Partners, L.P. (3620; 1340) and two purchases of the Shares by Financial Institution Partners III, L.P. (2080; 700).  The beneficial ownership of these Shares is more fully set out in the following footnote.</footnote>
        <footnote id="F2">SDH is the managing member (MM) of Hovde Capital, L.L.C., the general partner to Financial Institution Partners II, L.P., which owns 328,719 Shares; SDH is the MM of Hovde Capital Limited IV LLC, the general partner to Financial Institution Partners IV, L.P., which owns 51,970 Shares; SDH is the MM of Hovde Capital, Ltd., the general partner to Financial Institution Partners III, L.P., which owns 227,116 Shares; SDH is the MM of Hovde Capital IV, LLC, the general partner to Financial Institution Partners, L.P., which owns 419,307 Shares; SDH is the MM to Hovde Capital Offshore LLC, the management company to Financial Institution Partners, Ltd., which owns 117,950 Shares; SDH is the MM of Hovde Acquisition II, L.L.C., which owns 30,000 Shares; SDH is the trustee to The Hovde Financial, Inc. Profit Sharing Plan and Trust, which owns 19,000 Shares; SDH is the trustee to The Eric D. and Steven D. Hovde Foundation, which owns 21,265 Shares.</footnote>
    </footnotes>

    <remarks>All of the Shares reported herein as being beneficially owned by Steven D. Hovde have also been reported as being beneficially owned by Eric D. Hovde on a Form 4 of even date herewith.</remarks>

    <ownerSignature>
        <signatureName>STEVEN D. HOVDE</signatureName>
        <signatureDate>2006-08-01</signatureDate>
    </ownerSignature>
</ownershipDocument>
