<?xml version="1.0"?><ownershipDocument><schemaVersion>X0201</schemaVersion>    <documentType>4</documentType><periodOfReport>2003-10-21</periodOfReport><notSubjectToSection16>0</notSubjectToSection16><issuer><issuerCik>0000799166</issuerCik><issuerName>MASSBANK CORP</issuerName>        <issuerTradingSymbol>MASB</issuerTradingSymbol></issuer><reportingOwner><reportingOwnerId><rptOwnerCik>0001235383</rptOwnerCik><rptOwnerName>LAPIDUS LEONARD</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>0</isOfficer><isTenPercentOwner>0</isTenPercentOwner><isOther>0</isOther></reportingOwnerRelationship></reportingOwner><derivativeTable><derivativeTransaction><securityTitle><value>Phantom Stock</value><footnoteId id="F1" /></securityTitle><conversionOrExercisePrice><value>39.16</value></conversionOrExercisePrice><transactionDate><value>2003-10-21</value></transactionDate><deemedExecutionDate></deemedExecutionDate><transactionCoding><transactionFormType>4</transactionFormType><transactionCode>A</transactionCode><equitySwapInvolved>0</equitySwapInvolved></transactionCoding><transactionTimeliness><value></value></transactionTimeliness><transactionAmounts><transactionShares><value>38.3044</value></transactionShares><transactionPricePerShare><value>39.16</value></transactionPricePerShare><transactionAcquiredDisposedCode><value>A</value></transactionAcquiredDisposedCode></transactionAmounts><exerciseDate><footnoteId id="F2" /></exerciseDate><expirationDate><footnoteId id="F2" /></expirationDate><underlyingSecurity><underlyingSecurityTitle><value>Common</value></underlyingSecurityTitle><underlyingSecurityShares><value>38.3044</value></underlyingSecurityShares></underlyingSecurity><postTransactionAmounts><sharesOwnedFollowingTransaction><value>1246.0086</value><footnoteId id="F3" /></sharesOwnedFollowingTransaction></postTransactionAmounts><ownershipNature><directOrIndirectOwnership><value>D</value></directOrIndirectOwnership></ownershipNature></derivativeTransaction></derivativeTable><footnotes><footnote id="F1">Cash-only security issued pursuant to the Directors'Deferred Compensation Plan</footnote><footnote id="F2">The shares of phantom stock become payable in shares of common stock of the issuer upon the reporting person attaining the age of 72, or his termination or death or upon a change of control of the issuer</footnote><footnote id="F3">Includes 9.1072 shares of MASSBANK Corp Common Stock acquired on 05/22/2003 at a price of $30.06 per share and 8.3240 shares of MASSBANK Corp Common Stock acquired on 08/13/2003 at a price of $33.14 per share pursuant to the reinvestment of dividends under the Directors' Deferred Compensation Plan</footnote></footnotes><remarks></remarks><ownerSignature><signatureName>Leonard Lapidus</signatureName><signatureDate>2003-10-23</signatureDate></ownerSignature></ownershipDocument>

