Incorporating the Effect of Taxes on the Costs of Capital: Jorge Ricard, a financial analyst, is estimating the costs of capital for the Zeale Corporation. In the process of this estimation, Ricard has estimated the before-tax costs of capital for Zeales debt and equity as 4 percent and 6 percent, respectively. What are the after-tax costs of debt and equity if Zeales marginal tax rate is: a) 30 percent and b) 48 percent d. t = 30% - after-tax cost of debt = 4%, after-tax cost of equity = 4.2%; t = 48% - after-tax cost of debt =4%, after-tax cost of equity =3.12% a. t = 30% - after-tax cost of debt = 4%, after-tax cost