<SEC-DOCUMENT>0001179110-17-003260.txt : 20170227
<SEC-HEADER>0001179110-17-003260.hdr.sgml : 20170227
<ACCEPTANCE-DATETIME>20170227170123
ACCESSION NUMBER:		0001179110-17-003260
CONFORMED SUBMISSION TYPE:	4
PUBLIC DOCUMENT COUNT:		1
CONFORMED PERIOD OF REPORT:	20170224
FILED AS OF DATE:		20170227
DATE AS OF CHANGE:		20170227

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

REPORTING-OWNER:	

	OWNER DATA:	
		COMPANY CONFORMED NAME:			Polsky Howard D.
		CENTRAL INDEX KEY:			0001419879

	FILING VALUES:
		FORM TYPE:		4
		SEC ACT:		1934 Act
		SEC FILE NUMBER:	001-33883
		FILM NUMBER:		17642795

	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>2017-02-24</periodOfReport>

    <notSubjectToSection16>0</notSubjectToSection16>

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

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001419879</rptOwnerCik>
            <rptOwnerName>Polsky Howard D.</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>General Counsel &amp; Secretary</officerTitle>
            <otherText></otherText>
        </reportingOwnerRelationship>
    </reportingOwner>

    <nonDerivativeTable>
        <nonDerivativeTransaction>
            <securityTitle>
                <value>Common Stock</value>
            </securityTitle>
            <transactionDate>
                <value>2017-02-24</value>
            </transactionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>F</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
                <footnoteId id="F1"/>
            </transactionCoding>
            <transactionAmounts>
                <transactionShares>
                    <value>902</value>
                </transactionShares>
                <transactionPricePerShare>
                    <value>18.08</value>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>D</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>116050</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>2017-02-27</signatureDate>
    </ownerSignature>
</ownershipDocument>
</XML>
</TEXT>
</DOCUMENT>
</SEC-DOCUMENT>
