Common Form 4868 Mistakes and How to Avoid Them

The mistakes, and the fixes

1. Filing it late

Form 4868 has to be filed by the original due date: April 15, 2027, or June 15, 2027 if you're out of the country or a 1040-NR filer without U.S. wages. The IRS denies a late one. File your return as soon as you can instead.

2. Leaving off the address

The IRS can't process a Form 4868 without an address. Fill in line 1 completely.

3. No Social Security number

Without an SSN or ITIN, the IRS writes to ask for one and returns the form. If you don't have one, write "ITIN TO BE REQUESTED."

4. A name that doesn't match

Changed your name? Report it to the Social Security Administration before you file, or processing can be delayed. For e-filing, use your name exactly as the SSA has it.

5. An unreasonable estimate

If the IRS finds your line 4 estimate wasn't reasonable, the extension is void. Use your actual documents.

6. Counting this payment twice

Line 5 is what you'd already paid. The payment you're sending now goes on line 7 only.

7. Thinking it extends the time to pay

It doesn't. Pay what you owe by April 15, 2027, or interest and the late-payment penalty apply.

8. Skipping the extension because you can't pay

The late-filing penalty is usually about 10 times the late-payment penalty each month. File the extension, then pay what you can.

9. Wrong mailing address

The address depends on where you live and whether a payment is enclosed, and several changed on the 2025 form. Look it up each year.

10. Using a courier for a P.O. box

Private delivery services can't deliver to P.O. boxes, and the payment addresses are P.O. boxes. Use the U.S. Postal Service.

11. Filing twice

If you e-filed, or paid online and marked it as an extension, don't mail a paper form too (unless you e-filed and are mailing a check).

12. Two forms for a joint return

Married couples filing jointly need one Form 4868 with both names and SSNs.

13. The wrong form

Businesses that file their own return use Form 7004. Sole proprietors use Form 4868.

14. The wrong year's form

Form 4868 is dated by tax year. Use the form for the year you're extending.

15. Attaching it to the return

Don't attach Form 4868 to your return. Report any payment on Schedule 3, line 10.

16. Forgetting the state

A federal extension doesn't cover every state. Check your state.

A 30-second check before you mail it

• Postmark by the due date.
• Name(s), address and SSN(s) complete.
• Line 4 from your documents; line 6 is line 4 minus line 5.
• The right address for your state and payment choice.
• A copy and a mailing receipt for your records.