Please see IRS Tax Tip 2018-118, August 1, 2018, What taxpayers should know about amending a tax return for updated information. Summertime Tax Tip 2014-24, August 27, 2014 Don’t worry if you made a mistake on your tax return or forgot to claim a tax credit or deduction. You can fix it by filing an amended return. Here are 10 tips that you should know about amending your federal tax return: When to amend. You should amend your tax return if you need to correct your filing status, the number of dependents you claimed, or your total income. You should also amend your return to claim tax deductions or tax credits that you did not claim when you filed your original return. The instructions for Form 1040X, Amended U.S. Individual Income Tax Return, list more reasons to amend a return. When NOT to amend. In some cases, you don’t need to amend your tax return. The IRS usually corrects math errors when processing your original return. If you didn’t include a required form or schedule, the IRS will send you a request for the missing item. Form to use. Use Form 1040-X to amend a federal income tax return that you previously filed. Make sure you check the box at the top of the form that shows which year you are amending. Since you can’t e-file an amended return, you’ll need to file your Form 1040X on paper and mail it to the IRS. More than one year. If you file an amended return for more than one year, use a separate 1040X for each tax year. Mail them in separate envelopes to the IRS. See "Where to File" in the instructions for Form 1040X for the correct address to use. Form 1040X. Form 1040X has three columns. Column A shows amounts from the original return. Column B shows the net increase or decrease for the amounts you are changing. Column C shows the corrected amounts. You should explain what you are changing and the reasons why on the back of the form. Other forms or schedules. If your changes involve other tax forms or schedules, make sure you attach them to Form 1040X when you file the form. Failure to do this will cause a delay in processing. Amending to claim an additional refund. If you are waiting for a refund from your original tax return, don’t file your amended return until after you receive the refund. You may cash the refund check from your original return. Amended returns take up to 12 weeks to process. You will receive any additional refund you are owed. Amending to pay additional tax. If you’re filing an amended tax return because you owe more tax, you should file Form 1040X and pay the tax as soon as possible. This will limit any interest and penalty charges. When to file. To claim a refund, you generally must file Form 1040X within three years from the date you filed your original tax return. You can also file it within two years from the date you paid the tax, if that date is later than the three-year rule. Track your return. You can track the status of your amended tax return three weeks after you file with ‘Where’s My Amended Return?’ This tool is available on IRS.gov or by phone at 866-464-2050. Visit IRS.gov to get Form 1040-X or call 800-TAX-FORM (800-829-3676). More IRS resources Tax Topic 308 - Amended Returns Amended Returns & Form 1040-X – Frequently Asked Questions IRS YouTube Videos: Amending My Return – English | Spanish | ASL (obsolete Subscribe to IRS Tax Tips