<?xml version="1.0"?>

<ownershipDocument>

    <documentType>4</documentType>

    <periodOfReport>2003-07-23</periodOfReport>


    <notSubjectToSection16>0</notSubjectToSection16>

    <issuer>
        <issuerCik>0000720671</issuerCik>
        <issuerName>HALIFAX CORP</issuerName>
        <issuerTradingSymbol>HX</issuerTradingSymbol>
    </issuer>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001173152</rptOwnerCik>
            <rptOwnerName>FOLEY HUGH  M</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>  </rptOwnerStreet1>
            <rptOwnerStreet2>  </rptOwnerStreet2>
            <rptOwnerCity>  </rptOwnerCity>
            <rptOwnerState>  </rptOwnerState>
            <rptOwnerZipCode>  </rptOwnerZipCode>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>0</isDirector>
            <isOfficer>1</isOfficer>
            <isTenPercentOwner>0</isTenPercentOwner>
            <isOther>0</isOther>
            <officerTitle>Vice President</officerTitle>
        </reportingOwnerRelationship>
    </reportingOwner>

    <nonDerivativeSecurity>
        <securityTitle>
            <value>Halifax Corporation Common Stock</value>
        </securityTitle>
        <transactionDate>
            <value>2003-07-23</value>
        </transactionDate>
        <transactionCoding>
            <transactionFormType>4</transactionFormType>
            <transactionCode>P</transactionCode>
            <equitySwapInvolved>0</equitySwapInvolved>
        </transactionCoding>
        <transactionTimeliness>
            <value></value>
        </transactionTimeliness>
        <transactionAmounts>
            <transactionShares>
                <value>12165</value>
            </transactionShares>
            <transactionValue>
                <value>4.11</value>
            </transactionValue>
            <transactionAcquiredDisposedCode>
                <value>A</value>
            </transactionAcquiredDisposedCode>
        </transactionAmounts>
        <postTransactionAmounts>
            <sharesOwnedFollowingTransaction>
                <value>12165</value>
            </sharesOwnedFollowingTransaction>
        </postTransactionAmounts>
        <ownershipNature>
            <directOrIndirectOwnership>
                <value>I</value>
            </directOrIndirectOwnership>
            <natureOfOwnership>
                <value>Hugh Foley SEP/IRA</value>
            </natureOfOwnership>
        </ownershipNature>
    </nonDerivativeSecurity>

    <derivativeSecurity>
        <securityTitle>
            <value>Warrants for Halifax Corporation Common Stock</value>
        </securityTitle>
        <conversionOrExercisePrice>
            <value>4.93</value>
        </conversionOrExercisePrice>
        <transactionDate>
            <value>2003-07-23</value>
        </transactionDate>
        <transactionCoding>
            <transactionFormType>4</transactionFormType>
            <transactionCode>P</transactionCode>
            <equitySwapInvolved>0</equitySwapInvolved>
        </transactionCoding>
        <transactionTimeliness>
            <value></value>
        </transactionTimeliness>
        <transactionAmounts>
            <transactionShares>
                <value>2433</value>
            </transactionShares>
            <transactionValue>
                <value>4.93</value>
            </transactionValue>
            <transactionAcquiredDisposedCode>
                <value>A</value>
            </transactionAcquiredDisposedCode>
        </transactionAmounts>
        <exerciseDate>
            <value>2003-07-24</value>
        </exerciseDate>
        <expirationDate>
            <value>2008-07-24</value>
        </expirationDate>
        <underlyingSecurity>
            <underlyingSecurityTitle>
                <value>Halifax Corporation Common Stock</value>
            </underlyingSecurityTitle>
            <underlyingSecurityShares>
                <value>2433</value>
            </underlyingSecurityShares>
        </underlyingSecurity>
        <postTransactionAmounts>
            <sharesOwnedFollowingTransaction>
                <value>19933</value>
            </sharesOwnedFollowingTransaction>
        </postTransactionAmounts>
        <ownershipNature>
            <directOrIndirectOwnership>
                <value>I</value>
            </directOrIndirectOwnership>
            <natureOfOwnership>
                <value>Hugh Foley SEP/IRA</value>
            </natureOfOwnership>
        </ownershipNature>
    </derivativeSecurity>


    <ownerSignature>
        <signatureName>Hugh M. Foley</signatureName>
        <signatureDate>2003-07-24</signatureDate>
    </ownerSignature>

</ownershipDocument>

