If a taxpayer makes a mistake on their federal income tax return, they generally have to file an amended tax return to correct the error. In some cases, a superseded tax return is another option. 

Taxpayers can submit amended income tax returns for Form 1040, Form 1120, Form 1065, Form 1120-S, and Form 1041.

Individual taxpayers filing Form 1040 can amend their tax returns using Form 1040-X (Amended US Individual Income Tax Return). An amended tax return is filed anytime after the original return or previously amended return. Some taxpayers may file an amended tax return several times for the same tax year because they keep discovering errors.

Some circumstances do not require the taxpayer to file an amended return because the IRS corrects the errors automatically. The IRS website provides an Interactive Tax Assistant to help taxpayers understand whether they need to submit an amended tax return.  

Statute of Limitations on Amended Tax Returns

If filing an amended return results in a tax refund or a credit, the taxpayer must submit the amended return within three years after filing the original return or within two years after paying the tax, whichever is later. 

Example Fact Pattern for Amended Form 1040

John Taxpayer is preparing to file his 2023 Form 1040 (US Individual Income Tax Return), which is due April 15, 2024. On April 15, 2024, John decides to file an extension request via Form 4868. The extended deadline for filing his Form 1040 is now October 15, 2024. John files his Form 1040 on September 20, 2024.

9 months later on June 1, 2025, John discovered an error on his 2023 federal tax return. He incorrectly double-counted capital gains on the sale of stock.

John sold 50 shares of Meta Platforms Inc. on March 17, 2023, for $200 per share. John originally purchased the shares in October 2019 for $180 per share. John’s long-term capital gain (LTCG) information on the sale was as follows:

  • Proceeds: $10,000 (50 shares times $200)
  • Cost Basis: $9,000 (50 shares times $180)
  • Capital Gain: $1,000 ($10,000 proceeds minus $9,000 cost basis).

John inadvertently reported the information twice on his Form 8949 (Sale and Dispositions of Capital Assets) , effectively reporting $2,000 of LTCG when it should have been only $1,000. John should prepare Form 1040-X to correct Form 8949 and Schedule D (Capital Gains & Losses).

John cannot use the superseded return option because he’s correcting the errors after the October 15, 2024 deadline. 

Other Information on Amended Tax Returns

Taxpayers looking for more information on amended tax filings can view the Form 1040-X Instructions and IRS Topic 308.