Accelerated Depreciation and the Cost of Capital
用简化方式推导资本成本，从经济角度解释加速折旧如何降低企业资本成本，并将递延公司税视为一种融资来源。
The effects of various investment incentives-particularly accelerated depreciation-on the cost of capital of a profit-maximizing firm have been widely discussed during the last few years. Recent contributions include those of Sandmo (1974), Bergstrom (1976), Boadway (1978) and Alworth (1979). A shortcoming of these contributions, however, is that few efforts are made to provide economic interpretations of the results obtained. In this note, I derive the cost of capital in a simplified way in terms of a standard marginal investment project. The emphasis is on explaining the effects of accelerated depreciation on capital cost in economic terms.' The deferral of corporation tax brought about by acceleration of depreciation allowances is often compared to the acquisition of an interest-free loan from the Treasury. The deferred corporate tax is thus regarded as a source of finance to the firm. It turns out that the effects of accelerated depreciation on capital cost may well be interpreted in a way that conforms to this intuitive view of tax deferral. By means of a general expression for capital cost as a weighted average of the costs of debt and equity, the deferred corporate tax may be conceived of as a substitute for either equity or debt (or both).