Notice 2023-21. For the following affected taxpayers, Notice

2023-21 increases the lookback period when amending 2020 returns to claim a credit or refund of taxes. Affected taxpayers are individual taxpayers whose returns were due on April 15, 2021, and who did not receive a filing extension. An affected taxpayer who filed their 2020 return after April 15, 2021, but on or before May 17, 2021, because of the postponement provided by Notice 2021-21 may be refunded all income tax payments for 2020 if they file their claim for refund within 3 years of the date they filed their original return. An affected taxpayer who filed their 2020 return after May 17, 2021, may be refunded all income tax payments for 2020 if they file their claim for refund by Friday, May 17, 2024. The additional time, provided in Notice 2023-21, to file an amended return is automatic. Taxpayers do not need to contact the IRS, file any form, or send letters or other documents to receive this relief.

Time to file for a refund or credit if you reported certain qualified wildfire relief payments as taxable income. The Federal Disaster Tax Relief Act of 2023 extended the time for

Instructions for Form 1040-X (Rev. December 2025) 3

certain taxpayers to amend their returns with respect to qualified wildfire relief payments they received and reported as income in tax years 2020 and 2021. Taxpayers only had until December 12, 2025, or until the expiration of the period of limitations on filing a refund claim under section 6511 of the Internal Revenue Code for the relevant year, whichever is later, to file amended returns claiming a credit or refund. For tax years 2022 through 2025, to claim a refund of any taxes paid on qualified wildfire relief payments, individuals have until the expiration of the period of limitations on filing a refund claim under section 6511(a) for the relevant year. See Q5 and A5 of Wildlife Relief Payments and Casualty Losses frequently asked questions , at IRS.gov. Also, see the 2025 Instructions for Form 4684, Casualties and Thefts; and the 2025 Pub. 547, Casualties, Disasters, and Thefts.

Combat zones and contingency operations. The due date for claiming a credit or refund on your amended return may be automatically extended when you are in, or are hospitalized as a result of injuries sustained in, a combat zone or contingency operation. For more details, see Pub. 3, Armed Forces' Tax Guide.

Bad debt or worthless security. A Form 1040-X to claim a credit or refund based on a bad debt or worthless security must generally be filed within 7 years after the due date of the return for the tax year in which the debt or security became worthless. For more details, see section 6511.

Foreign tax credit or deduction. A Form 1040-X to claim a foreign tax credit or to change from claiming a deduction to claiming a credit for foreign income taxes must generally be filed within 10 years from the due date for filing the return (without regard to any extension of time to file) for the year in which the foreign income taxes were actually paid or accrued. A Form 1040-X to claim a deduction or to change from claiming a credit to claiming a deduction for foreign income taxes must generally be filed within 3 years after the date you filed your original return or within 2 years after the date you paid the tax, whichever is later. The period for filing a Form 1040-X to claim or change an election to claim a foreign tax credit or deduction may be extended by an agreement. You make or change your election on your Form 1040-X for the year your election is to be effective. For details, see Pub. 514, Foreign Tax Credit for Individuals. The extended 10-year period for filing Form 1040-X to claim a foreign tax credit or to change from claiming a deduction to claiming a credit applies only to amounts affected by changes in your foreign tax credit. P.L. 119-21, section 70311, has modified the foreign tax credit. See the Instructions for Form 1116, Foreign Tax Credit, for more information.

If you are filing Form 1040-X to carry back your unused foreign tax credit, follow the procedures under Loss or credit carryback next.

Loss or credit carryback. File either Form 1040-X or Form 1045 to apply for a refund based on either an overpayment of tax due to a claim of right adjustment under section 1341(b)(1) or the carryback of a net operating loss (NOL) (but see Net operating losses, later), a foreign tax credit, an unused general business credit, or a net section 1256 contracts loss. If you use Form 1040-X, see the special instructions for carryback claims in these instructions under Special Situations, later. File Form 1040-X for each tax year to which an NOL, a capital loss carryback, a credit carryback, or a foreign tax credit is carried. Write or type “Carryback Claim” at the top of page 1. Form 1040-X must generally be filed within 3 years after the due date of the return (including extensions) for the tax year in which the NOL, capital loss, or unused credit arose (within 10 years after the due date of the return (without extensions) for the tax year in which the foreign tax credit arose). If you use Form 1045, you must file the claim within 1 year after the end of the year in which

the loss, credit, or claim of right adjustment arose. For more details, see the Instructions for Form 1045.

Net operating losses (NOLs). An individual must file Form 1040-X instead of Form 1045 to carry back:

• Any items to a section 965 year,

• A prior year foreign tax credit released due to an NOL or net capital loss carryback, or

• A prior year general business credit released because of the release of the foreign tax credit.

See section 172 and Pub. 536 for information about NOLs. See Pub. 225, Farmer’s Tax Guide, for information on farming losses.