three years
The IRS advises that you generally must file Form 1040X to amend a return 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. Be sure to enter the year of the return you are amending at the top of Form 1040X.

You generally must file an amended return within three years of the date you filed the original return or within two years after the date you paid the tax, whichever is later.

Can you file an amended tax return for 2020?

Only Tax Year 2019 and 2020 1040 and 1040-SR returns can be amended electronically at this time. Amended Returns for any other tax years or tax types must be filed by paper. There must be a record of an “original” electronically filed return for Tax Year 2019 or Tax Year 2020.

What do I need to amend my federal tax return?

Use Form 1040X to amend a federal income tax return that you filed before. 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.

Can you file an amended tax return electronically?

If you need to amend your 2019 or 2020 Forms 1040 or 1040-SR you can now file the Form 1040-X, Amended U.S. Individual Income Tax Return electronically using available tax software products. What are some reasons that an Amended Return cannot be filed electronically? Amended Returns must be filed by paper for the following reasons:

When do I have to file my 2015 tax return?

Returns filed before the due date (without regard to extensions) are considered filed on the due date. example Robert’s 2015 tax return was due April 15, 2016. He filed it on March 20, 2016. He amends the 2015 return, expecting the correction to result in a refund.