Capital income taxation, depreciation allowances and economic growth: A perfect-foresight general equilibrium model

The results indicated in Table 1 show that incomplete depreciation allowances reinforce the distortions in the equilibrium growth path brought about by an ideal capital income tax. A reduction in the deductible share of economic depreciation, like an increase in the tax rate, raises the current level of consumption, but reduces the steady state levels of consumption and capital per efficiency unit of labour. The reason for these distortions is that the tax law is able to drive wedges both between the rate of time preference and the market rate of interest, and between the latter and the marginal productivity of capital. The first wedge is created through capital income taxation as such and its size is directly related to the tax rate. The second wedge is created by the incomplete deductibility of depreciation. Its size is directly related to the tax rate and inversely to the deductible share of depreciation. For the distortion in the growth path of the economy it is the sum of the two wedges that counts. Therefore it is plausible that incomplete depreciation allowances reinforce the effects of capital income taxation. Knowing the determinants of the two wedges one can easily derive the influence of a tax reform on the marginal productivity of capital, the market rate of interest and the rate of time preference (cf. Table 2). In the short run, the system of these three interest rates is anchored by the marginal productivity of capital, and hence any measure that widens a wedge is translated into a reduction in the rate or those rates below the wedge. In the long run the system is anchored by the rate of time preference and an increase in the width of a wedge is translated into an increase in those rates or that rate above this wedge.