<?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>0001202543</rptOwnerCik>
            <rptOwnerName>HOLLEY RICK R</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>1411 E MISSION AVE</rptOwnerStreet1>
            <rptOwnerStreet2></rptOwnerStreet2>
            <rptOwnerCity>SPOKANE</rptOwnerCity>
            <rptOwnerState>WA</rptOwnerState>
            <rptOwnerZipCode>99220</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>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>A</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>3157</value>
                    <footnoteId id="F3"/>
                </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 compenstation utilizing &quot;new issue&quot; stock price.  The price per share (per LTIP) is the closing price Friday, September 2, 2011.</footnote>
        <footnote id="F2">Shares issued as part of Mr. Holley's director retainer.</footnote>
        <footnote id="F3">Share total increased by 1,000 shares which were directly held prior to becoming board member - as reported on Form 3 May 28, 2011</footnote>
    </footnotes>

    <ownerSignature>
        <signatureName>/s/ Rick R. Holley</signatureName>
        <signatureDate>2011-09-07</signatureDate>
    </ownerSignature>
</ownershipDocument>
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X0304
4
2011-09-06
0
0000104918
AVISTA CORP
AVA
0001202543
HOLLEY RICK R
1411 E MISSION AVE
SPOKANE
WA
99220
1
0
0
0
Common Stock
2011-09-06
4
A
0
249
24.03
A
3157
D
Shares issued under the Long Term Incentive Plan (LTIP) as an award of stock for director compenstation utilizing "new issue" stock price.  The price per share (per LTIP) is the closing price Friday, September 2, 2011.
Shares issued as part of Mr. Holley's director retainer.
Share total increased by 1,000 shares which were directly held prior to becoming board member - as reported on Form 3 May 28, 2011
/s/ Rick R. Holley
2011-09-07