This paper studies how frictions, both real and financial, interact with capital tax policy in a dynamic, general equilibrium model with heterogeneous firms. Comparative statics show that tax policy can have substantially different effects depending upon the frictions present. Analytical and numerical exercises show that accounting for firm heterogeneity is important when evaluating the responses of economic aggregates to capital tax policy. The effects of tax cuts on allocational efficiency are found to be quantitatively significant, often accounting for the majority of the change in output following a reduction in taxes on capital.