"This report has two main objectives: First, to determine whether the real tax rate on investment income has proven sensitive to inflation; second, to determine the extent to which real returns to debt and equity, based on published data, differ from those based on inflation-adjusted data. The scope of the inflationary distortion in corporate income is assessed, and the resulting estimate is used to calculate the real after-tax rate of return on Canadian corporate debt and equity for the 1966-80 period. The author departs from previous studies of the Canadian corporate sector in his definition of returns to corporate activity. His definition reflects the view that the cost of corporate capital is governed by the after-tax returns accruing to individual investors from their debt and equity claims on the corporate sector. Two empirical regularities are found: 1) the real after-tax rate of return on debt and equity calculated with full inflation accounting is consistently below the rate based on unadjusted data; and, 2) the inflation-adjusted real tax rate on investment income appears to increase with inflation over the sample period." -- Abstract.