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CAUTION

New IP PINs are generated every year. They will generally be sent out by mid-January. Use this IP PIN on any Form 1040-X you file.

Requirements for a Paper Return You must handwrite your signature on your return if you file it on paper. Digital, electronic, or typed-font signatures are not valid signatures for Forms 1040-X filed on paper.

Requirements for an Electronic Return To file your return electronically, you must sign the return electronically using a personal identification number (PIN) and provide the information described below. If you are filing online using software, you must use a Self-Select PIN. If you are filing electronically using a tax practitioner, you can use a Self-Select PIN or a Practitioner PIN. If we issued you an IP PIN for the year, all six digits of your IP PIN must appear in the IP PIN spaces provided next to the space for your occupation for your electronic signature to be complete. Do not use an IP PIN from a prior year, even if amending a return filed in a prior year. Failure to include an issued IP PIN on the electronic return will result in an invalid signature and a rejected return. If you are filing a joint return and both taxpayers were issued IP PINs, enter both IP PINs in the spaces provided.

TIP

For e-filed Forms 1040-X, your software will continue to select the order of your forms and attachments. For paper-filed Forms 1040-X, see below.

You must place behind your completed paper-filed Form 1040-X a completed and updated Form 1040, 1040-SR, or 1040-NR with the changes you are submitting.

For paper-filed Forms 1040-X, assemble any new or changed schedules and forms behind your completed, updated Form 1040, 1040-SR, or 1040-NR in the order of the “Attachment Sequence No.” shown in the upper-right corner of the schedule or form. If you have supporting statements, arrange them in the same order as the schedules or forms they support and attach them last. Don’t attach a copy of your original return, correspondence, or other items unless required to do so.

Attach to the front of Form 1040-X:

• A copy of any Form W-2; Form W-2c; or Form 2439, Notice to Shareholder of Undistributed Long-Term Capital Gains, that supports changes made on this return;

Instructions for Form 1040-X (Rev. December 2025) 11

• A copy of any Form W-2G, Certain Gambling Winnings; or Form 1099-R that supports changes made on this return, but only if tax was withheld; and

• A copy of any Form 1042-S, Foreign Person's U.S. Source Income Subject to Withholding; Form SSA-1042S, Social Security Benefit Statement (Nonresident Aliens); Form RRB-1042S, Payments by the Railroad Retirement Board (Nonresident Aliens); or Form 8288-A, Statement of Withholding on Dispositions by Foreign Persons of U.S. Real Property Interests, that supports changes made on this return.

Attach to the back of Form 1040-X any Form 8805, Foreign Partner's Information Statement of Section 1446 Withholding Tax, that supports changes made on this return.

If you owe tax and you don’t want to pay electronically, enclose (don’t attach) your check or money order in the envelope with your amended return. See Line 20 , earlier.