depreciation, in accounting, reduction in the value of fixed or capital assets, as by use, damage, weathering, or obsolescence. It can be estimated according to a number of methods. In the straight-line method, depreciation is simply seen as a function of time; the cost of the asset, minus its value as scrap, is divided by an estimate of its life. Other methods distribute depreciation over the life of the asset by gradually increasing, or gradually diminishing, installments. The resale value of a machine generally declines most quickly during its early years; thus its depreciation is measured in decreasing installments. The opposite is true of rights of limited duration, such as copyrights and leaseholds, whose value depreciates most quickly as their date of expiration approaches. The technical name for the depreciation of such nonmaterial rights is amortization. The problem of calculating depreciation has special importance because of the need for accuracy in income tax returns. Failure to make allowance for depreciation results in overestimating income. Depreciation of money is brought about by a decline in the price of a particular currency in terms of other currencies, thereby lowering the foreign exchange value of the first currency.
See J. D. Coughlan, Depreciation (1969); R. P. Brief, ed., Depreciation and Capital Maintenance (1984).