To sign a federal tax return, use the “Sign Here” block at the bottom of page two of Form 1040. On a paper return, that means an original ink signature; if you e-file, you sign with a five-digit Self-Select PIN, or by signing Form 8879 if a paid preparer submits the return for you. Either way, an unsigned return is treated as invalid and the IRS will send it back before processing.1Internal Revenue Service. IRS Policy Statement on Unsigned Income Tax Returns
Where the Signature Goes on Form 1040
The signature block sits at the bottom of page two. It has a line for your signature, a line for the date, and fields for your occupation and a daytime phone number. Those extra fields help the IRS confirm your identity and reach you if something on the return needs clarification.2Internal Revenue Service. IRS Courseware – Link and Learn Taxes – Taxpayer Signature
If you file jointly, both spouses must sign on their designated lines. A joint return with only one signature is not valid.2Internal Revenue Service. IRS Courseware – Link and Learn Taxes – Taxpayer Signature
Directly below the taxpayer signature area is a separate block for any paid preparer. The preparer signs, dates the form, and enters their Preparer Tax Identification Number, along with the firm’s name and Employer Identification Number. If you prepared the return yourself, leave that block empty.
Paper Returns Need an Ink Signature
If you mail Form 1040, the IRS wants an original ink signature, sometimes called a wet signature. A photocopied signature won’t do. If your return arrives without a physical signature, the IRS won’t process it; they’ll mail it back and ask you to sign and resend, which can push your refund out by weeks.1Internal Revenue Service. IRS Policy Statement on Unsigned Income Tax Returns
For a joint paper return, both spouses have to sign the same physical document before it goes in the envelope. One signature means the return is incomplete.
How to Sign When You E-File
When you e-file, your electronic signature is a Self-Select PIN. You choose any five-digit number other than all zeros, and that number is your signature on the return.3Internal Revenue Service. Self-Select PIN Method for Forms 1040 and 4868 Modernized e-File
To prove you’re the real taxpayer, the software will also ask for your date of birth and one of two verification items: your adjusted gross income from last year’s return, or the Self-Select PIN you used last year. First-time filers should enter zero for the prior-year AGI. Leaving the field blank will cause the IRS to reject the return.
If the IRS has issued you an Identity Protection PIN, enter that six-digit number when prompted. The IP PIN takes the place of the AGI or prior-year-PIN check. IP PINs change every year, so pull the current one from your IRS online account before you file.4Internal Revenue Service. Topic No. 255, Signing Your Return Electronically
When a Preparer E-Files for You: Form 8879
If a paid preparer submits your return electronically, you sign Form 8879, the IRS e-file Signature Authorization. That form gives the preparer permission to enter or generate a PIN and transmit the return.5Internal Revenue Service. About Form 8879, IRS e-file Signature Authorization It carries a perjury statement, so signing it has the same legal weight as signing the return directly.
Your preparer keeps Form 8879 for three years from either the return’s due date or the date the IRS received it, whichever is later.6Internal Revenue Service. Form 8879-PE – IRS e-file Signature Authorization The form isn’t sent to the IRS unless the agency asks for it. Keep your own copy, too: if you later need to prove your e-filed return was properly authorized, Form 8879 is the document that shows it.7Internal Revenue Service. Form 8879 – IRS e-file Signature Authorization
Signing on Someone Else’s Behalf
A handful of situations call for someone other than the taxpayer to sign. Each has its own rule.
A Minor Child
If a child can’t sign their own return, a parent or guardian signs the child’s name in the signature space and adds “By [parent’s signature], parent for minor child” next to it.8Internal Revenue Service. Return Signature
A Deceased Taxpayer
A final return for someone who has died is signed by a court-appointed representative, a surviving spouse, or the person managing the deceased’s property. Write “deceased,” the person’s name, and the date of death across the top of the return. A court-appointed representative attaches a copy of the court document showing the appointment. With no appointed representative and no surviving spouse, whoever is in charge of the property signs as “personal representative.” Anyone claiming a refund who isn’t a surviving spouse or court-appointed representative also has to file Form 1310.9Internal Revenue Service. Filing a Final Federal Tax Return for Someone Who Has Died
Power of Attorney
Someone holding your power of attorney (Form 2848) generally cannot sign your return for you. The IRS permits it only in narrow situations: you have a disease or injury that prevents you from signing, you’ve been outside the United States continuously for at least 60 days before the filing deadline, or the IRS grants specific permission for another reason. When one of those applies, the representative checks the box on line 5a of Form 2848 and attaches it to the return with a written explanation.10Internal Revenue Service. Instructions for Form 2848, Power of Attorney and Declaration of Representative
What Happens If You Forget to Sign
An unsigned return is not a valid return. The IRS won’t process it, and no refund goes out until the signature is fixed.2Internal Revenue Service. IRS Courseware – Link and Learn Taxes – Taxpayer Signature In most cases the IRS sends Letter 12C asking you to provide the missing signature within 20 days. Respond to the letter rather than filing an amended return. After the IRS receives your signed response, plan on another six to eight weeks for the refund.11Internal Revenue Service. Understanding Your Letter 12C
The bigger risk is timing. While the return sits unprocessed, late-filing penalties can still accrue. The failure-to-file penalty is 5% of the unpaid tax for each month or partial month the return is late, capped at 25%.12Office of the Law Revision Counsel. 26 USC 6651 – Failure to File Tax Return or to Pay Tax For returns required to be filed in 2026, if the return is more than 60 days late, the minimum penalty is the lesser of $525 or 100% of the tax you owe.13Internal Revenue Service. Topic No. 653, IRS Notices and Bills, Penalties and Interest Charges An unsigned return that stalls for months can trigger these charges even if you thought you filed on time.
What You’re Actually Signing
Right above the signature line is a declaration that you’re signing under penalty of perjury that the return is true, correct, and complete. It isn’t boilerplate. Under federal law, anyone who willfully signs a return they know to be materially false commits a felony, punishable by a fine of up to $100,000 (or $500,000 for a corporation) and up to three years in prison.14Office of the Law Revision Counsel. 26 USC 7206 – Fraud and False Statements The operative word is “willfully.” Honest mistakes don’t trigger criminal prosecution, but deliberately inflating deductions or hiding income can.