The after-tax required rate of return on equity of a form is less than its after-tax required rate of return on debt. Suppose that the firm has bonds with an annual coupon rate that is equal to the annual Yield to Maturity of those bonds. Regarding the Weighted Average Cost of Capital (WACC) of the form: All else the same, WACC will increase as the bonds of the firm approach maturity. All else the same, using the Book (Face) Value of the debt will give us higher WACC than using the Market Value of the debt. All else the same, WACC will decrease as the bonds of the firm approach maturity. All else the same, using the Book (Face) Value of the debt will give us the same WACC as using the Market Value of the debt. All else the same, using the Book (Face) Value of the debt will give us lower WACC than using the Market Value of the debt