income and franchise tax provisions are allocable to contracts in process and , accordingly , are included in general and administrative expenses . deferred income taxes are recorded when revenues and expenses are recognized in different periods for financial statement purposes than for tax return purposes . deferred tax asset or liability account balances are calculated at the balance sheet date using current tax laws and rates in effect . determinations of the expected realizability of deferred tax assets and the need for any valuation allowances against these deferred tax assets were evaluated based upon the stand-alone tax attributes of the company , and valuation allowances of $ 21 million and $ 18 million were deemed necessary as of december 31 , 2012 and 2011 , respectively . uncertain tax positions meeting the more-likely-than-not recognition threshold , based on the merits of the position , are recognized in the financial statements . we recognize the amount of tax benefit that is greater than 50% ( 50 % ) likely to be realized upon ultimate settlement with the related tax authority . if a tax position does not meet the minimum statutory threshold to avoid payment of penalties , we recognize an expense for the amount of the penalty in the period the tax position is claimed or expected to be claimed in our tax return . penalties , if probable and reasonably estimable , are recognized as a component of income tax expense . we also recognize accrued interest related to uncertain tax positions in income tax expense . the timing and amount of accrued interest is determined by the applicable tax law associated with an underpayment of income taxes . see note 11 : income taxes . under existing gaap , changes in accruals associated with uncertainties are recorded in earnings in the period they are determined . cash and cash equivalents - the carrying amounts of cash and cash equivalents approximate fair value due to the short-term nature of these items , having original maturity dates of 90 days or less . accounts receivable - accounts receivable include amounts billed and currently due from customers , amounts currently due but unbilled , certain estimated contract change amounts , claims or requests for equitable adjustment in negotiation that are probable of recovery , and amounts retained by the customer pending contract completion . inventoried costs - inventoried costs primarily relate to work in process under contracts that recognize revenues using labor dollars or units of delivery as the basis of the percentage-of-completion calculation . these costs represent accumulated contract costs less cost of sales , as calculated using the percentage-of-completion method . accumulated contract costs include direct production costs , factory and engineering overhead , production tooling costs , and , for government contracts , allowable general and administrative expenses . according to the provisions of the company's u.s . government contracts , the customer asserts title to , or a security interest in , inventories related to such contracts as a result of contract advances , performance-based payments , and progress payments . in accordance with industry practice , inventoried costs are classified as a current asset and include amounts related to contracts having production cycles longer than one year . inventoried costs also include company owned raw materials , which are stated at the lower of cost or market , generally using the average cost method . property , plant , and equipment - depreciable properties owned by the company are recorded at cost and depreciated over the estimated useful lives of individual assets . costs incurred for computer software developed or obtained for internal use are capitalized and amortized over the expected useful life of the software , not to exceed nine years . leasehold improvements are amortized over the shorter of their useful lives or the term of the lease . the remaining assets are depreciated using the straight-line method , with the following lives: .
wha is the percentage change in the valuation allowance from 2011 to 2012?
the company evaluates the recoverability of its property , plant and equipment when there are changes in economic circumstances or business objectives that indicate the carrying value may not be recoverable . the company's evaluations include estimated future cash flows , profitability and other factors in determining fair value . as these assumptions and estimates may change over time , it may or may not be necessary to record impairment charges. .