Ready to sign your tax return? That feels like an easy lift—but some quirks and exceptions can make it challenging for some taxpayers. Here’s what you need to know.

Why It Matters For Taxpayers

A missed or incorrect signature may not feel like a big deal, but it’s a common mistake that taxpayers make at tax time. And there are real-world consequences.

If you file a return without a signature, the IRS will treat it as if it were not filed at all. That means the statute of limitations does not start (extending the time the IRS has to review your return and collect the tax), and late-filing penalties may apply. And if you’re waiting on a tax refund? If you have to resubmit due to a signature goof, expect processing delays.

Signing Your Paper Return

The general rule for signing a federal income tax return is straightforward: The taxpayer must sign and date the return. If you’re signing a paper Form 1040, you’ll find the signature block at the bottom of the second page (for a Form 1040-SR, the signature block is at the bottom of the third page). The IRS requires “wet ink,” meaning that you must sign the original copy by hand—digital, electronic, or typed-font signatures are not valid signatures for Form 1040 or 1040-SR filed on paper.

Don’t assume that not being able to hold a pen properly or not being able to physically sign a return due to a disability or illiteracy means that you can't sign your tax return. You may still be able to. An X mark is legally valid in most states as a signature. If all you can manage is an X, that's your legal signature.

Of course, it helps to have that signature witnessed (and some states may require it) in case there are any questions. But there's nothing in the law that says that your signature must look a certain way, no matter what my fifth-grade teacher had me believe.

Signing Your Electronic Return

If you’re filing electronically, you must still sign the return, but you’ll use a Personal Identification Number (PIN) rather than a handwritten signature.

If you are filing online using DIY software, you’ll use a Self-Select PIN, meaning one that you create yourself. If you are filing electronically using a tax practitioner, you can use a Self-Select PIN or a Practitioner PIN. The PIN should be a combination of five numbers, with one exception: the IRS will not allow you to choose five zeros.

To e-file with a Self-Select PIN, you’ll also need to include your date of birth and your adjusted gross income (AGI) from your prior year return—this helps protect you from someone else filing without your permission. You’ll find your AGI on line 11 of the return. If you don’t have your last year’s return handy, you can access your transcript using your online account at irs.gov.

You can’t use the Self-Select PIN method if you are a first-time filer under age 16 at the end of 2025

If you’re using a paid preparer, they can enter or generate your PIN for you. You’ll also sign Form 8879, which shows that you have allowed the preparer to e-file on your behalf. (This form doesn’t get mailed to the IRS, but is retained by your tax preparer to show that you’ve given permission for them to e-file.)

Don’t Forget Your IP PIN

If the IRS issued you an identity protection personal identification number, or IP PIN (a six-digit number that is assigned to you to protect against identity theft), all six digits of your IP PIN must appear on the return. If you don’t do that, the return will be rejected.

If you are filing a joint return and both taxpayers were issued an IP PIN, you’ll enter both IP PINs in the spaces provided.

New IP PINs are generated every year. They will generally be sent out by mid-January following the tax year (around the same time you’ll get your tax forms). If you misplace or forget your IP PIN, you can find instructions for retrieving it online at IRS.gov/IPPIN or by calling 800-908-4490.

Jointly Filed Tax Returns

If you are filing a joint return, your spouse must also sign the tax return. The signatures should follow the order in which the names appear on the return.

If you’re filing a joint return and one spouse cannot sign due to travel, incapacity, or other reason, the other spouse may sign on their behalf if they have a valid power of attorney that specifically authorizes the signing of a tax return. In that case, the signature line should say something like, “John Doe, by Jane Doe, attorney-in-fact.”

In the absence of a power of attorney, if a spouse is unable to sign due to injury or disease, the other spouse may sign the return and must attach a statement explaining the circumstances and confirming that the nonsigning spouse consents to the filing.

Simply being away does not permit one spouse to sign for the other without proper authorization. This is true even when there are practical limitations, like serving in the military—consider getting a power of authority if you anticipate that your spouse won't be around in time to sign the returns.

You may also have more time to file. If you are a U.S. citizen or resident who lives outside of the U.S. or Puerto Rico, or if you are active duty military and live outside of the U.S., you qualify for an automatic two-month extension. Members of the military and others serving in combat zones or hazardous zone areas generally have until at least 180 days after they leave the zone to file returns and to pay any taxes due.

Special rules apply when a taxpayer is deceased. If a joint return is filed for the year of death, the surviving spouse should sign the return and indicate that they are filing as the surviving spouse. If a personal representative, such as an executor or administrator, has been appointed, that individual must also sign the return.

For a deceased taxpayer who was not filing jointly, the return is generally signed by the court-appointed personal representative of the estate.

If the deceased taxpayer is due a refund and no personal representative has been appointed, you’ll want to include Form 1310, Statement of Person Claiming Refund Due a Deceased Taxpayer.

Taxpayers Who Are Minors

When the taxpayer is a minor, the return remains the child’s return, and the child should sign if they’re able to do so. (Remember, it doesn’t have to be a fantastic signature, just a signature.)

If the child cannot sign, a parent or legal guardian may sign on the child’s behalf, indicating their relationship. If you’re the child’s parent, that typically looks like, “By (your signature), parent for minor child.”

Taxpayers Who Are Incompetent or Incapacitated

In situations involving an incompetent or incapacitated taxpayer, a duly appointed guardian, conservator, or other fiduciary may sign the return. The authority must be tied to a legal appointment, such as a court order, rather than informal caregiving or assistance.

You’ll want to prove to the IRS that you have the authority to sign on behalf of the taxpayer—that’s typically done by including Form 56. Again, you must have legal authority, and not just simply “helping out.”

If you’re the court-appointed representative, you’ll generally sign the return like this: “By (your signature), guardian of Jane Doe.”

Using A Paid Preparer

If you use a paid preparer, that preparer must also sign the return and include their preparer tax identification number (PTIN). This requirement is in addition to the signature requirement and does not replace your signature.

Someone who prepares your return but doesn’t charge you—like your mom or favorite sister who is also a tax preparer—shouldn’t sign your return.

© Forbes