You do your best to file a correct tax return. You gather all your W-2s, 1099s, receipts and other documents and navigate through all of the information to find the right schedules and forms. Sometimes, however, new information arises after you file your tax return. Maybe you discovered a tax credit you didn't realize you qualified for, or missed a 1099 form because it came in late. Fortunately, the IRS has a simple process in place that allows you to amend your tax return.