What should you do if you already filed your federal tax return and then discover a mistake? First of all, don’t worry. In most cases, all you have to do is file an amended tax return. But before you do that, here is what you should be aware of when filing an amended tax return.

Taxpayers should use Form 1040X, Amended U.S. Individual Income Tax Return, to file an amended (corrected) tax return.

You must file the corrected tax return on paper. An amended return cannot be e-filed. If you need to file another schedule or form, don’t forget to attach it to the amended return.

An amended tax return should only be filed to correct errors or make changes to your original tax return. For example, you should amend your return if you need to change your filing status, or correct your income, deductions or credits.

You normally do not need to file an amended return to correct math errors because the IRS automatically makes those changes for you. Also, do not file an amended return because you forgot to attach tax forms, such as W-2s or schedules. The IRS normally will mail you a request asking for those.

Note: Eligible taxpayers who filed a 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. The IRS may contact you to ask for a copy of your corrected Form 1095-A to verify the information.

Nonetheless, you may choose to file an amended return because some taxpayers may find that filing an amended return may reduce their tax owed or give them a larger refund (see below for additional information).

If you are amending more than one tax return, prepare a separate 1040X for each return and mail them to the IRS in separate envelopes. Note the tax year of the return you are amending at the top of Form 1040X. You will find the appropriate IRS address to mail your return to in the Form 1040X instructions.

If you are filing an amended tax return to claim an additional refund, wait until you have received your original tax refund before filing Form 1040X. Amended returns take up to 16 weeks to process. You may cash your original refund check while waiting for the additional refund.

If you owe additional taxes with Form 1040X, file it and pay the tax as soon as possible to minimize interest and penalties. You can use IRS Direct Pay to pay your tax directly from your checking or savings account.

Generally, you must file Form 1040X within three years from the date you filed your original tax return or within two years of the date you paid the tax, whichever is later. For example, the last day for most people to file a 2013 claim for a refund is April 17, 2017. Special rules may apply to certain claims. For more information see the instructions for Form 1040X or call the office.

You can track the status of your amended tax return for the current year three weeks after you file. You can also check the status of amended returns for up to three prior years. To use the “Where’s My Amended Return” tool on the IRS website, just enter your taxpayer identification number (usually your Social Security number), date of birth and zip code. If you have filed amended returns for more than one year, you can select each year individually to check the status of each.

Filing an amended return after receiving a corrected Form 1095-A

If you enrolled in qualifying Marketplace health coverage, then you probably filed a tax return based on a Form 1095-A that you received from the Marketplace.

Some taxpayers may receive a second Form 1095-A because the information on their initial form was incorrect or incomplete. If you filed a 2015 tax return based on the initial Form 1095-A and claimed the premium tax credit using incorrect information from either the federally-facilitated or a state-based Health Insurance Marketplace, you should determine the effect the changes to your form might have on your return. Comparing the two Forms 1095-A can help you assess whether you should file an amended tax return, Form 1040X.

Corrected Form 1095-A

A corrected form generally indicates you previously received a Form 1095-A containing one or more errors.

• If you have not yet filed your tax return, you should use this new form when completing your tax return.
• If you have already filed your tax return, you will need to determine the effect the changes to your form might have on your return. Some changes–such as a corrected address–may not affect your tax return or require any action on your part, while others–such as a change in your monthly premium amount–might. Compare the corrected Form 1095-A to the original form to determine the nature of the change. For a detailed list of these changes, see Corrected or Voided Form 1095-A. This information can help you assess whether you should file an amended tax return, Form 1040X. If you are uncertain whether you should amend your tax return, you may want to consult with a tax preparer.
• If you believe the information on your corrected Form 1095-A is incorrect or you have question about the form, you should contact your Marketplace.

Voided Form 1095-A

A voided form–or letter stating your form was voided–generally indicates you previously received a Form 1095-A that was issued in error. This may happen if you did not complete enrollment in Marketplace coverage. The voided Form 1095-A, as the well as the previously received Form 1095-A, should not be used to file your tax return.

• If you receive a voided Form 1095-A after you have already filed your tax return and claimed the premium tax credit using the original Form 1095-A that the Marketplace sent in error, you should file an amended return.
• If you have not yet filed your tax return, don’t use the information on the voided or on the previously received Form 1095-A to figure a premium tax credit on Form 8962.
• If you had coverage through the Marketplace and you believe they should not have voided your form, you should contact your Marketplace immediately to receive an accurate Form 1095-A.

Please call if you need assistance filing an amended return or have any questions about Form 1040X.