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

    <schemaVersion>X0202</schemaVersion>

    <documentType>4</documentType>

    <periodOfReport>2006-01-04</periodOfReport>

    <notSubjectToSection16>0</notSubjectToSection16>

    <issuer>
        <issuerCik>0000799166</issuerCik>
        <issuerName>MASSBANK CORP</issuerName>
        <issuerTradingSymbol>MASB</issuerTradingSymbol>
    </issuer>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001134600</rptOwnerCik>
            <rptOwnerName>BRANDI GERARD H</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>C/O MASSBANK CORP</rptOwnerStreet1>
            <rptOwnerStreet2>123 HAVEN STREET</rptOwnerStreet2>
            <rptOwnerCity>READING</rptOwnerCity>
            <rptOwnerState>MA</rptOwnerState>
            <rptOwnerZipCode>01867</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>1</isDirector>
            <isOfficer>1</isOfficer>
            <isTenPercentOwner>0</isTenPercentOwner>
            <isOther>0</isOther>
            <officerTitle>President, Chairman &amp; CEO</officerTitle>
        </reportingOwnerRelationship>
    </reportingOwner>

    <nonDerivativeTable>
        <nonDerivativeTransaction>
            <securityTitle>
                <value>common stock</value>
            </securityTitle>
            <transactionDate>
                <value>2006-01-04</value>
            </transactionDate>
            <deemedExecutionDate></deemedExecutionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>J</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
                <footnoteId id="F1"/>
            </transactionCoding>
            <transactionTimeliness>
                <value></value>
            </transactionTimeliness>
            <transactionAmounts>
                <transactionShares>
                    <value>5000</value>
                </transactionShares>
                <transactionPricePerShare>
                    <value>15.50</value>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>A</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>235107.971</value>
                    <footnoteId id="F2"/>
                    <footnoteId id="F3"/>
                    <footnoteId id="F4"/>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
            </ownershipNature>
        </nonDerivativeTransaction>
    </nonDerivativeTable>

    <derivativeTable>
        <derivativeTransaction>
            <securityTitle>
                <value>Option (right to buy)</value>
            </securityTitle>
            <conversionOrExercisePrice>
                <value>15.50</value>
            </conversionOrExercisePrice>
            <transactionDate>
                <value>2006-01-04</value>
            </transactionDate>
            <deemedExecutionDate></deemedExecutionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>J</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
                <footnoteId id="F1"/>
            </transactionCoding>
            <transactionTimeliness>
                <value></value>
            </transactionTimeliness>
            <transactionAmounts>
                <transactionShares>
                    <value>5000</value>
                </transactionShares>
                <transactionPricePerShare>
                    <value>15.50</value>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>D</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <exerciseDate>
                <value>1996-01-16</value>
            </exerciseDate>
            <expirationDate>
                <value>2006-01-15</value>
            </expirationDate>
            <underlyingSecurity>
                <underlyingSecurityTitle>
                    <value>common</value>
                </underlyingSecurityTitle>
                <underlyingSecurityShares>
                    <value>5000</value>
                </underlyingSecurityShares>
            </underlyingSecurity>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>0</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
            </ownershipNature>
        </derivativeTransaction>
    </derivativeTable>

    <footnotes>
        <footnote id="F1">Exercise of stock option granted under the MASSBANK Corp. Stock Option Plan</footnote>
        <footnote id="F2">Includes 28,221.354 shares owned indirectly by Gerard H. Brandi under the MASSBANK Employee Stock Ownership Plan (ESOP).</footnote>
        <footnote id="F3">Also includes 18,048.749 shares of common stock of MASSBANK Corp. stock owned by Mr. Brandi's spouse, to which Mr. Brandi disclaims beneficial ownership. This report shall not be deemed an admission that Mr. Brandi is the beneficial owner of these shares. This share position includes the following shares acquired during 2005 pursuant to the reinvestment of dividends under the MASSBANK Corp Dividend Reinvestment Plan: 103.214 sh @$38.00 per sh on 02/18/05; 108.997 sh @$36.2301 per sh on 05/19/05; 115.072 sh @$34.5636 on 08/18/05; and 136.328 sh @$30.5246 sh on 11/17/05.</footnote>
        <footnote id="F4">Also includes 1,570.137 shares of common stock of MASSBANK Corp. stock owned indirectly by Mr. Brandi as custodian for minors. This share position includes the following shares acquired during 2005 pursuant to the reinvestment of dividends under the MASSBANK Corp Dividend Reinvestment Plan: 10.40 sh @$38.00 per sh on 02/18/05; 10.984 sh @$36.2301 per sh on 05/19/05; 11.599 sh @$34.5636 on 08/18/05; and 13.739 sh @$30.5246 sh on 11/17/05.</footnote>
    </footnotes>

    <remarks></remarks>

    <ownerSignature>
        <signatureName>Gerard H. Brandi</signatureName>
        <signatureDate>2006-01-06</signatureDate>
    </ownerSignature>
</ownershipDocument>
