second hirm s marginal tax rate not 40%? E4-20. Suppose a C corporation has a tax loss of $5 million in the current period. The firm's after-tax discount rate is 10%. Assume the firm is allowed to carry back losses. Over the preceding 5 years, the firm reported the following taxable income: Year -5 -4 -3 -2 Current -1 Taxable income ($ millions) $1.0 $1.0 $1.5 $4.0 $3.0 -$5.0 Statutory tax rate 40% 40% 35% 35% 30% 30% a. If the carryback period is 3 years, what is the firm's marginal tax rate in the current period? b. If the carryback period is 2 years, what is the firm's marginal tax rate in the current period? c. Suppose the firm is prohibited from carrying back losses, what is its marginal tax rate assuming it will earn $2 million in each of the next 5 years? d. Suppose the carryback period is 2 years and taxable income in period -1 was only $1 million. What is the firm's marginal tax rate in the current period