IRS Practice & Procedure

On April 2, 20x1, Sam filed his 20x0 income tax return, which showed a tax due of $40,000. On June 1, 20x3, Sam filed an amended return for 20x0 that showed an additional tax of $12,000. Sam paid the additional amount. On May 18, 20x4, Sam files a claim for a refund of $18,000.

a. If Sams claim for a refund is correct, how much tax will he recover?

b. For what period will interest run in regard to Sams claim for a refund?