-----BEGIN PRIVACY-ENHANCED MESSAGE-----
Proc-Type: 2001,MIC-CLEAR
Originator-Name: webmaster@www.sec.gov
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 TWSM7vrzLADbmYQaionwg5sDW3P6oaM5D3tdezXMm7z1T+B+twIDAQAB
MIC-Info: RSA-MD5,RSA,
 M5kZCWJ7VacaHaWg6rAchW14RyRLu7qZ2bmIr/S/meZnY+tkGXnx0GyERkR++mK4
 whoAz6/pbLVaXpWn4n6lMw==

<SEC-DOCUMENT>0001058690-07-000017.txt : 20070430
<SEC-HEADER>0001058690-07-000017.hdr.sgml : 20070430
<ACCEPTANCE-DATETIME>20070430174917
ACCESSION NUMBER:		0001058690-07-000017
CONFORMED SUBMISSION TYPE:	4
PUBLIC DOCUMENT COUNT:		1
CONFORMED PERIOD OF REPORT:	20070426
FILED AS OF DATE:		20070430
DATE AS OF CHANGE:		20070430

REPORTING-OWNER:	

	OWNER DATA:	
		COMPANY CONFORMED NAME:			Niemer Joseph W
		CENTRAL INDEX KEY:			0001336871

	FILING VALUES:
		FORM TYPE:		4
		SEC ACT:		1934 Act
		SEC FILE NUMBER:	000-24503
		FILM NUMBER:		07802353

	BUSINESS ADDRESS:	
		BUSINESS PHONE:		(360) 679-3121

	MAIL ADDRESS:	
		STREET 1:		PO BOX 7001
		CITY:			OAK HARBOR
		STATE:			WA
		ZIP:			98277

ISSUER:		

	COMPANY DATA:	
		COMPANY CONFORMED NAME:			WASHINGTON BANKING CO
		CENTRAL INDEX KEY:			0001058690
		STANDARD INDUSTRIAL CLASSIFICATION:	STATE COMMERCIAL BANKS [6022]
		IRS NUMBER:				911725825
		STATE OF INCORPORATION:			WA
		FISCAL YEAR END:			1231

	BUSINESS ADDRESS:	
		STREET 1:		450 SW BAYSHORE DR
		CITY:			OAK HARBOR
		STATE:			WA
		ZIP:			98277
		BUSINESS PHONE:		3606793121

	MAIL ADDRESS:	
		STREET 1:		450 SW BAYSHORE DR
		CITY:			OAK HARBOR
		STATE:			WA
		ZIP:			98277
</SEC-HEADER>
<DOCUMENT>
<TYPE>4
<SEQUENCE>1
<FILENAME>doc.xml
<DESCRIPTION>PRIMARY DOCUMENT
<TEXT>
<XML>
<?xml version="1.0"?>
<ownershipDocument>

    <schemaVersion>X0202</schemaVersion>

    <documentType>4</documentType>

    <periodOfReport>2007-04-26</periodOfReport>

    <issuer>
        <issuerCik>0001058690</issuerCik>
        <issuerName>WASHINGTON BANKING CO</issuerName>
        <issuerTradingSymbol>WBCO</issuerTradingSymbol>
    </issuer>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001336871</rptOwnerCik>
            <rptOwnerName>Niemer Joseph W</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>450 SW BAYSHORE DRIVE</rptOwnerStreet1>
            <rptOwnerStreet2></rptOwnerStreet2>
            <rptOwnerCity>OAK HARBOR</rptOwnerCity>
            <rptOwnerState>WA</rptOwnerState>
            <rptOwnerZipCode>98277</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>0</isDirector>
            <isOfficer>1</isOfficer>
            <isTenPercentOwner>0</isTenPercentOwner>
            <isOther>0</isOther>
            <officerTitle>CCO</officerTitle>
            <otherText></otherText>
        </reportingOwnerRelationship>
    </reportingOwner>

    <nonDerivativeTable>
        <nonDerivativeHolding>
            <securityTitle>
                <value>Common Stock</value>
            </securityTitle>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>1497</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
            </ownershipNature>
        </nonDerivativeHolding>
    </nonDerivativeTable>

    <derivativeTable>
        <derivativeTransaction>
            <securityTitle>
                <value>Restricted Stock Units</value>
            </securityTitle>
            <conversionOrExercisePrice>
                <footnoteId id="F1"/>
            </conversionOrExercisePrice>
            <transactionDate>
                <value>2007-04-26</value>
            </transactionDate>
            <deemedExecutionDate></deemedExecutionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>A</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
            </transactionCoding>
            <transactionTimeliness>
                <value></value>
            </transactionTimeliness>
            <transactionAmounts>
                <transactionShares>
                    <value>876</value>
                </transactionShares>
                <transactionPricePerShare>
                    <value>0</value>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>A</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <exerciseDate>
                <value>2008-04-26</value>
                <footnoteId id="F2"/>
            </exerciseDate>
            <expirationDate>
                <value>2012-04-26</value>
            </expirationDate>
            <underlyingSecurity>
                <underlyingSecurityTitle>
                    <value>Common Stock</value>
                </underlyingSecurityTitle>
                <underlyingSecurityShares>
                    <value>876</value>
                </underlyingSecurityShares>
            </underlyingSecurity>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>876</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
            </ownershipNature>
        </derivativeTransaction>
    </derivativeTable>

    <footnotes>
        <footnote id="F1">Each Restricted Stock Unit represents a contingent right to receive one share of WBCO common stock.</footnote>
        <footnote id="F2">The restricted stock units vest over 5 years in 20% portions annually.</footnote>
    </footnotes>

    <ownerSignature>
        <signatureName>Shelly L Angus as Attorney-in-Fact for Joseph W. Niemer</signatureName>
        <signatureDate>2007-04-30</signatureDate>
    </ownerSignature>
</ownershipDocument>
</XML>
</TEXT>
</DOCUMENT>
</SEC-DOCUMENT>
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