What’s New

New attachment requirement. For paper-filed Forms 1040-X, you must attach, to your completed Form 1040-X, a completed and updated Form 1040, 1040-SR, or 1040-NR, with your changes. See Assembling Your Return , later.

Form 4547, Trump Account Election(s). Do not attach Form 4547 to Form 1040-X. See the Instructions for Form 4547 for more information on how to file Form 4547 after your return has been filed or go to trumpaccounts.gov.

Line 4a and Line 4b. The qualified business income deduction is now discussed in Line 4a , later. Line 4b, later, discusses the new deductions for tips, overtime, car loan interest, and seniors on new Schedule 1-A (Form 1040).

Form 8379, Injured Spouse Allocation. Form 8379 may be filed electronically by attaching it to an electronically filed Form 1040-X even if the filer is not amending their tax return.

State-declared disasters. If you were affected by a qualified State-declared disaster, you may have additional time to file a claim for credit or refund on your amended return. See State-declared disasters , later.

Lookback period. The lookback period for claiming refunds and credits has been extended in certain situations. See Filing limits due to lookback period , later.

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 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

Instructions for Form 1040-X (Rev. 12-2025) Catalog Number 11362H Feb 27, 2026 Department of the Treasury Internal Revenue Service www.irs.gov

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.

Domestic research and experimental expenditures. P.L. 119-21, commonly known as the One Big Beautiful Bill Act (OBBBA), added section 174A, Domestic Research or Experimental Expenditures. Under this new section, certain small business taxpayers have the option to elect to deduct certain unamortized amounts paid or incurred in tax years beginning after 2021 and before 2025. If you have already filed a tax return for the year, you will need to amend your return. The deadline for making the election is July 6, 2026. See Rev. Proc. 2025-28 for more information.