Thomas received $30,000 in a legal settlement in 2003. The tax treatment of the item is not certain. Thomas's research results were ambiguous so he is not sure the income is taxable. Because some doubt remained and because he did not think he would be audited, Thomas took the position that the income was not taxable and did not include it on his tax return filed on April 14, 2004. His gross income, excluding the $30,000 in question, is $50,000.

a. When does the statute of limitations expire for Tom's 2003 tax return?

b. Would your answer change if Thomas were certain the amount was taxable, but decided to exclude it from his return anyway?