Answer:
When calculating the cost of debt, a company needs to adjust for taxes, because interest payments are deductible by the paying corporation
Step-by-step explanation:
A debt on which the company pays interest, will be tax deductible.
The reason is that the interest are treated as expense thus, reducing the taxable income. While the dividends to preferred or common stock don't.
The formula for after-tax cost of debt:
pre-tax cost ( 1 - tax-rate ) = after-tax
example, if a bon pays 10% and the tax rate is 25%
0.10 ( 1- 0.25) = 0.10 x 0.75 = 0.075 = 7.5%
The real cost of debt is 7.5 because, the tax shield offered from the interest.