Abstract
This paper makes the case for the close involvement of engineers in the financial appraisal of proposals for capital expenditure on plant and machinery. Post-tax assessments are now essential for the great majority of companies and this requires a coherent analytical framework which encompasses both the tax cash flows and the impact of tax upon the cost of capital in an inflationary environment. This paper deals with the impact of taxation upon the cost of capital, the discount rate and the yield (internal rate of return) which forms an essential component of modern methods of discounted cash flow financial appraisal. A companion paper considers tax cash flows and shows that the net present value discounted at the net cost of capital may be distorted in comparison to the pre-tax NPV discounted at the gross cost of capital.