Discovering you’ve made a mistake on your tax return isn’t unusual. If you simply make a math error or forget to attach a W-2 or other form, you don’t need to file an amended return. The Internal Revenue Service will send you a notice if they need further information. However, if you missed a deduction, you should file an amended return. You may file amended returns for refunds up to three years after the original due date of your tax return or two years after you paid the taxes due, whichever is later. If you just filed your tax return and you expect a refund, wait until it arrives before filing an amended return. You can go ahead and cash the refund check.
Prepare corrected copies of forms or schedules affected by the missed deduction or other error. For example, if you missed a deduction for a capital loss from a stock investment, complete a corrected Schedule D, Capital Gains and Losses. You can download any forms you need on the IRS website.
Download and print a copy of IRS Form 1040X, Amended U.S. Individual Tax Return. Don’t fill out another regular 1040 form. You have to file a paper form to amend a tax return. There is no electronic filing option. Be sure you have the 1040X for the correct tax year and enter the year for which you are filing an amended return.
Fill out the 1040X form. This is a two-page form. On the first page are three columns for entering tax return information. Enter the amounts from each item of your original tax return in Column A. In column B, enter the dollar amount of any change. Enter the new amount in Column C. On the second page of the 1040X, use the space provided to explain each change you made to your original tax return.
Attach any corrected forms and schedules from Step 1. Sign and date the 1040X. Mail everything to the address given in the instructions. The IRS says it takes eight to 12 weeks to process an amended return.