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

    <schemaVersion>X0306</schemaVersion>

    <documentType>4</documentType>

    <periodOfReport>2014-09-12</periodOfReport>

    <notSubjectToSection16>0</notSubjectToSection16>

    <issuer>
        <issuerCik>0000104918</issuerCik>
        <issuerName>AVISTA CORP</issuerName>
        <issuerTradingSymbol>AVA</issuerTradingSymbol>
    </issuer>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001081485</rptOwnerCik>
            <rptOwnerName>BURKE DONALD C</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>1411 E. MISSION AVENUE</rptOwnerStreet1>
            <rptOwnerStreet2></rptOwnerStreet2>
            <rptOwnerCity>SPOKANE</rptOwnerCity>
            <rptOwnerState>WA</rptOwnerState>
            <rptOwnerZipCode>99202</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>1</isDirector>
            <isOfficer>0</isOfficer>
            <isTenPercentOwner>0</isTenPercentOwner>
            <isOther>0</isOther>
        </reportingOwnerRelationship>
    </reportingOwner>

    <nonDerivativeTable>
        <nonDerivativeTransaction>
            <securityTitle>
                <value>Common Stock</value>
            </securityTitle>
            <transactionDate>
                <value>2014-09-12</value>
            </transactionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>A</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
                <footnoteId id="F1"/>
            </transactionCoding>
            <transactionTimeliness>
                <value></value>
            </transactionTimeliness>
            <transactionAmounts>
                <transactionShares>
                    <value>32</value>
                    <footnoteId id="F2"/>
                </transactionShares>
                <transactionPricePerShare>
                    <value>32.61</value>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>A</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>9495</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
            </ownershipNature>
        </nonDerivativeTransaction>
    </nonDerivativeTable>

    <footnotes>
        <footnote id="F1">Shares issued under the Long Term Incentive Plan as an award of stock for Director Compensation.  The price per share is the closing price on September 11, 2014.</footnote>
        <footnote id="F2">Shares issued as part of Mr. Burke's Director retainer.</footnote>
    </footnotes>

    <ownerSignature>
        <signatureName>/s/Donald C. Burke</signatureName>
        <signatureDate>2014-09-12</signatureDate>
    </ownerSignature>
</ownershipDocument>
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X0306
4
2014-09-12
0
0000104918
AVISTA CORP
AVA
0001081485
BURKE DONALD C
1411 E. MISSION AVENUE
SPOKANE
WA
99202
1
0
0
0
Common Stock
2014-09-12
4
A
0
32
32.61
A
9495
D
Shares issued under the Long Term Incentive Plan as an award of stock for Director Compensation.  The price per share is the closing price on September 11, 2014.
Shares issued as part of Mr. Burke's Director retainer.
/s/Donald C. Burke
2014-09-12