Considerable interest has been expressed in recent years by tax theorists as well as practitioners, for the taxation of companies based on their cash flow. Unlike the equity-income tax base, which requires the deductibility of economic depreciation and debt financing costs, the cash-flow base expenses capital at the point of purchase, eliminating the need for the subsequent costing of this capital. This paper raises some of the issues that would arise in trying to implement a company tax either in the form of an indexed equity-income or a cash-flow tax. Issues raised include: (i) administrative complexity; (ii) international tax coordination and competition; and (iii) transition problems. In a closed economy the cash-flow tax seems a simple, efficient form of company taxation, administratively straightforward and neutral with regard to investment decisions. The more complicated equity-income tax is harder to defend in a closed economy.