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

    <schemaVersion>X0304</schemaVersion>

    <documentType>4</documentType>

    <periodOfReport>2011-09-06</periodOfReport>

    <notSubjectToSection16>0</notSubjectToSection16>

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

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001200812</rptOwnerCik>
            <rptOwnerName>RACICOT MARC F</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>2000 K STREET NW</rptOwnerStreet1>
            <rptOwnerStreet2>SUITE 500</rptOwnerStreet2>
            <rptOwnerCity>WASHINGTON</rptOwnerCity>
            <rptOwnerState>DC</rptOwnerState>
            <rptOwnerZipCode>20006</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>2011-09-06</value>
            </transactionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>A</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
                <footnoteId id="F1"/>
            </transactionCoding>
            <transactionTimeliness>
                <value></value>
            </transactionTimeliness>
            <transactionAmounts>
                <transactionShares>
                    <value>249</value>
                    <footnoteId id="F2"/>
                </transactionShares>
                <transactionPricePerShare>
                    <value>24.03</value>
                    <footnoteId id="F1"/>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>A</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>6587</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
            </ownershipNature>
        </nonDerivativeTransaction>
    </nonDerivativeTable>

    <footnotes>
        <footnote id="F1">Shares issued under the Long Term Incentive Plan (LTIP) as an award of stock for director compensation utilizing &quot;new issue&quot; stock price.  The price per share (per LTIP) is the closing price on Friday, September 2, 2011.</footnote>
        <footnote id="F2">Shares issued as part of Mr. Racicot's director retainer.</footnote>
    </footnotes>

    <ownerSignature>
        <signatureName>/s/ Marc Racicot</signatureName>
        <signatureDate>2011-09-07</signatureDate>
    </ownerSignature>
</ownershipDocument>
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X0304
4
2011-09-06
0
0000104918
AVISTA CORP
AVA
0001200812
RACICOT MARC F
2000 K STREET NW
SUITE 500
WASHINGTON
DC
20006
1
0
0
0
Common Stock
2011-09-06
4
A
0
249
24.03
A
6587
D
Shares issued under the Long Term Incentive Plan (LTIP) as an award of stock for director compensation utilizing "new issue" stock price.  The price per share (per LTIP) is the closing price on Friday, September 2, 2011.
Shares issued as part of Mr. Racicot's director retainer.
/s/ Marc Racicot
2011-09-07