table of contents statutory surplus the table below sets forth statutory surplus for the company 2019s insurance companies as of december 31 , 2012 and 2011: .
as of december 312012 what was the percent of the total statutory surplus for the company 2019s insurance companies property and casualty insurance subsidiaries
statutory capital and surplus for the u.s . life insurance subsidiaries , including domestic captive insurance subsidiaries , decreased by $ 978 , primarily due to variable annuity surplus impacts of approximately $ 425 , a $ 200 increase in reserves on a change in valuation basis , $ 200 transfer of the mutual funds business from the u.s . life insurance companies to the life holding company , and an increase in the asset valuation reserve of $ 115 . as a result of the january 2013 statutory gain from the sale of the retirement plans and individual life businesses , the company's pro forma january 2 , 2013 u.s . life statutory surplus was estimated to be $ 8.1 billion , before approximately $ 1.5 billion in extraordinary dividends and return of capital to hfsg holding company . statutory capital and surplus for the property and casualty insurance subsidiaries increased by $ 233 , primarily due to statutory net income , after tax , of $ 727 , unrealized gains of $ 249 , and an increase in statutory admitted deferred tax assets of $ 77 , capital contributions of $ 14 , and an increase of statutory admitted assets of $ 7 , partially offset by dividends to the hfsg holding company of $ 841 . both net income and dividends are net of interest payments and dividends , respectively , on an intercompany note between hartford holdings , inc . and hartford fire insurance company . the company also holds regulatory capital and surplus for its operations in japan . under the accounting practices and procedures governed by japanese regulatory authorities , the company 2019s statutory capital and surplus was $ 1.1 billion and $ 1.3 billion as of december 31 , 2012 and 2011 , respectively . statutory capital the company 2019s stockholders 2019 equity , as prepared using u.s . generally accepted accounting principles ( 201cu.s . gaap 201d ) was $ 22.4 billion as of december 31 , 2012 . the company 2019s estimated aggregate statutory capital and surplus , as prepared in accordance with the national association of insurance commissioners 2019 accounting practices and procedures manual ( 201cu.s . stat 201d ) was $ 14.1 billion as of december 31 , 2012 . significant differences between u.s . gaap stockholders 2019 equity and aggregate statutory capital and surplus prepared in accordance with u.s . stat include the following : 2022 u.s . stat excludes equity of non-insurance and foreign insurance subsidiaries not held by u.s . insurance subsidiaries . 2022 costs incurred by the company to acquire insurance policies are deferred under u.s . gaap while those costs are expensed immediately under u.s . 2022 temporary differences between the book and tax basis of an asset or liability which are recorded as deferred tax assets are evaluated for recoverability under u.s . gaap while those amounts deferred are subject to limitations under u.s . stat . 2022 the assumptions used in the determination of life benefit reserves is prescribed under u.s . stat , while the assumptions used under u.s . gaap are generally the company 2019s best estimates . the methodologies for determining life insurance reserve amounts may also be different . for example , reserving for living benefit reserves under u.s . stat is generally addressed by the commissioners 2019 annuity reserving valuation methodology and the related actuarial guidelines , while under u.s . gaap , those same living benefits may be considered embedded derivatives and recorded at fair value or they may be considered sop 03-1 reserves . the sensitivity of these life insurance reserves to changes in equity markets , as applicable , will be different between u.s . gaap and u.s . stat . 2022 the difference between the amortized cost and fair value of fixed maturity and other investments , net of tax , is recorded as an increase or decrease to the carrying value of the related asset and to equity under u.s . gaap , while u.s . stat only records certain securities at fair value , such as equity securities and certain lower rated bonds required by the naic to be recorded at the lower of amortized cost or fair value . 2022 u.s . stat for life insurance companies establishes a formula reserve for realized and unrealized losses due to default and equity risks associated with certain invested assets ( the asset valuation reserve ) , while u.s . gaap does not . also , for those realized gains and losses caused by changes in interest rates , u.s . stat for life insurance companies defers and amortizes the gains and losses , caused by changes in interest rates , into income over the original life to maturity of the asset sold ( the interest maintenance reserve ) while u.s . gaap does not . 2022 goodwill arising from the acquisition of a business is tested for recoverability on an annual basis ( or more frequently , as necessary ) for u.s . gaap , while under u.s . stat goodwill is amortized over a period not to exceed 10 years and the amount of goodwill is limited. .