This paper first refers to the key concept of recognition of asset losses under the corporate tax law. The tax law basically restricts the loss deduction and imposes requirements of "settlements" with a fact of physical or
monetary damage for the special loss deduction unless potential nonrecognized losses may be deducted under the accounting standards from the viewpoint of disclosure for asset fair values. This loss deduction rule is derived from the foreseeability and legal stability in calculation of taxable income. This paper secondly explains the content and legislative context of the recent amendments in the depreciation system and allowance expenses. Some allowance systems has been repealed in order to enlarge the tax base and
increase the tax revenue, however, the accelerated depreciation, newly introduced system in the recent corporate tax reform, brought a broad accrual expense, where it caused an opposite result to the tax base. I would rather
mention the background of the past tax reforms and suggest the range of estimated accrual expenses should be more broadened. Finally, this paper would clarify the contemporary signification in the loss deduction rule. ASBJ has issued the cumulative accounting standards for the global convergence, and is now required the final decision for the IFRS adoption. It would likely be said that harmonization between the accounting and tax enforcement would
be continuously pursed through this convergence process. The loss deduction rule would have a vital role in the fair value measurement in tax accounting, where tax income and each tax item on a balance sheet are measured by an index with high accuracy and legal settlement.