If you believe that the IRS is in error in its assessment of additional tax, you should respond to the letter, stating in detail the reasons for your disagreement and the tax result that you believe is correct. That may be done in a letter, supported with lists or schedules. If you think that an amended return would best illustrate your tax position, you may certainly prepare one and attach it to your response to the letter you have received.

Do not simply file an amended return without responding to the letter from the IRS.

If you know that you owe additional tax, even if you disagree with the IRS as to the exact amount, it is in your best interest to pay what you owe as soon as possible. The IRS will continue to accrue penalties and interest on the unpaid tax.