If you are due a refund from your original return, wait to get that refund before filing Form 1040X to claim an additional refund. If you use other IRS forms or schedules to make changes, make sure to attach them to your Form 1040X. Check the form’s instructions for where to mail your return. Note the tax year of the return you are amending at the top of Form 1040X. You should mail each year in separate envelopes. If you are amending more than one tax return, prepare a 1040X for each year. See the Form 1040X instructions for special rules that apply to some claims.

That means the last day for most people to file a 2013 claim for a refund is April 15, 2017. You can file it within two years from the date you paid the tax, if that date is later. You usually have three years from the date you filed your original tax return to file Form 1040X to claim a refund. The IRS may contact you to ask for a copy of your corrected Form 1095-A to verify the information. Eligible taxpayers who filed a 2014 or 2015 tax return and claimed a premium tax credit using incorrect information from either the federally-facilitated or a state-based Health Insurance Marketplace, generally do not have to file an amended return regardless of the nature of the error, even if additional taxes would be owed.

Most taxpayers don’t need to amend to correct Form 1095-A, Health Insurance Marketplace Statement, errors.

The IRS will mail you a request for them in most cases. Also, do not file an amended return if you forgot to attach tax forms, such as a Form W-2 or a schedule. The IRS will automatically correct those for you. You normally don’t need to file an amended return to correct math errors.

Don’t amend for math errors, missing forms.

For example, you should amend to change your filing status, or to correct your income, deductions or credits. You should file an amended tax return to correct errors or make changes to your original tax return. See the Form 1040X instructions for the address where you should mail your form. You must file a paper Form 1040X it can’t be e-filed. Individual Income Tax Return, to correct your tax return. Here are ten tips that can help you file.

Did you make an error on your federal tax return? If so, you may need to file an amended return.

Amended tax return status