<SEC-DOCUMENT>0001179110-17-011913.txt : 20170831
<SEC-HEADER>0001179110-17-011913.hdr.sgml : 20170831
<ACCEPTANCE-DATETIME>20170831161757
ACCESSION NUMBER:		0001179110-17-011913
CONFORMED SUBMISSION TYPE:	4
PUBLIC DOCUMENT COUNT:		1
CONFORMED PERIOD OF REPORT:	20170829
FILED AS OF DATE:		20170831
DATE AS OF CHANGE:		20170831

REPORTING-OWNER:	

	OWNER DATA:	
		COMPANY CONFORMED NAME:			Rhyu James Jeaho
		CENTRAL INDEX KEY:			0001443328

	FILING VALUES:
		FORM TYPE:		4
		SEC ACT:		1934 Act
		SEC FILE NUMBER:	001-33883
		FILM NUMBER:		171063577

	MAIL ADDRESS:	
		STREET 1:		2300 CORPORATE PARK DRIVE
		CITY:			HERNDON
		STATE:			VA
		ZIP:			20171

ISSUER:		

	COMPANY DATA:	
		COMPANY CONFORMED NAME:			K12 INC
		CENTRAL INDEX KEY:			0001157408
		STANDARD INDUSTRIAL CLASSIFICATION:	SERVICES-EDUCATIONAL SERVICES [8200]
		IRS NUMBER:				954774688
		STATE OF INCORPORATION:			DE
		FISCAL YEAR END:			0630

	BUSINESS ADDRESS:	
		STREET 1:		2300 CORPORATE PARK DRIVE
		CITY:			HERNDON
		STATE:			VA
		ZIP:			20171
		BUSINESS PHONE:		7034837000

	MAIL ADDRESS:	
		STREET 1:		2300 CORPORATE PARK DRIVE
		CITY:			HERNDON
		STATE:			VA
		ZIP:			20171
</SEC-HEADER>
<DOCUMENT>
<TYPE>4
<SEQUENCE>1
<FILENAME>edgar.xml
<DESCRIPTION>FORM 4 -
<TEXT>
<XML>
<?xml version="1.0"?>
<ownershipDocument>

    <schemaVersion>X0306</schemaVersion>

    <documentType>4</documentType>

    <periodOfReport>2017-08-29</periodOfReport>

    <notSubjectToSection16>0</notSubjectToSection16>

    <issuer>
        <issuerCik>0001157408</issuerCik>
        <issuerName>K12 INC</issuerName>
        <issuerTradingSymbol>LRN</issuerTradingSymbol>
    </issuer>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001443328</rptOwnerCik>
            <rptOwnerName>Rhyu James Jeaho</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>2300 CORPORATE PARK DRIVE</rptOwnerStreet1>
            <rptOwnerStreet2></rptOwnerStreet2>
            <rptOwnerCity>HERNDON</rptOwnerCity>
            <rptOwnerState>VA</rptOwnerState>
            <rptOwnerZipCode>20171</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>0</isDirector>
            <isOfficer>1</isOfficer>
            <isTenPercentOwner>0</isTenPercentOwner>
            <isOther>0</isOther>
            <officerTitle>EVP &amp; Chief Financial Officer</officerTitle>
            <otherText></otherText>
        </reportingOwnerRelationship>
    </reportingOwner>

    <nonDerivativeTable>
        <nonDerivativeTransaction>
            <securityTitle>
                <value>Common Stock</value>
            </securityTitle>
            <transactionDate>
                <value>2017-08-29</value>
            </transactionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>F</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
                <footnoteId id="F1"/>
            </transactionCoding>
            <transactionAmounts>
                <transactionShares>
                    <value>17581</value>
                </transactionShares>
                <transactionPricePerShare>
                    <value>17.44</value>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>D</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>213408</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
            </ownershipNature>
        </nonDerivativeTransaction>
    </nonDerivativeTable>

    <derivativeTable></derivativeTable>

    <footnotes>
        <footnote id="F1">Represents the number of shares withheld by the Company upon the vesting of restricted shares to cover the executive's withholding tax on income associated with the satisfaction of all vesting conditions. The number of shares withheld is based upon the closing price of a share of K12 common stock on the vesting date, or if the vesting date fell on a weekend or market holiday, upon the closing price of a share of K12 common stock on the most recent prior market day.</footnote>
    </footnotes>

    <ownerSignature>
        <signatureName>/s/ John C. Grothaus, attorney-in-fact</signatureName>
        <signatureDate>2017-08-31</signatureDate>
    </ownerSignature>
</ownershipDocument>
</XML>
</TEXT>
</DOCUMENT>
</SEC-DOCUMENT>
