Reese, a calendar-year taxpayer, uses the cash method of accounting for her sole proprietorship. In late December, she received a $65,000 bill from her accountant for consulting services related to her small business. Reese can pay the $65,000 bill anytime before January 30 of next year without penalty. Assume Reese's marginal tax rate is 32 percent this year and 35 percent next year, and that she can earn an after-tax rate of return of 12 percent on her investments.

Required:
a. What is the after-tax cost if she pays the $65,000 bill in December?
b. What is the after-tax cost if she pays the $65,000 bill in January?

To calculate after-tax costs we just need to deduct the tax saving amount from the pre-tax amount. The tax saving amount can be calculated bt multiplying the pre-tax amount into the tax rate

Requirement A (If she pays the $65,000 in December)

After-tax cost = Pre tax cost - PV of tax saving

After-tax cost = 65,000 - 20,800

After-tax cost = $44,200

working

Tax saving = $65,000 x 32%

Tax saving = $20,800

Requirement B (If she pays the $65,000 in January)

After tax cost = $65,000 - $20,315

After tax cost = $44,684

working

Tax saving = $65,000 x 35%

Tax saving = $22,750

Pv of tax saving = $22,750 x 0.893

Pv of tax saving = $20,316