Extended returns are due October 15 in most years, not April 15

If you file Form 4868 (Application for Automatic Extension of Time To File U.S. Individual Income Tax Return) before your regular deadline, the IRS gives you six additional months. For the 2024 tax year, that means your return is due October 15, 2025, instead of April 15, 2025. The extension pushes back the filing date only — not the payment date. If you owe taxes, they are still due on the original April 15 deadline, and you will owe interest and penalties on any unpaid balance after that date.

Form 4868 itself must reach the IRS by the original April 15 deadline. You can file it electronically through tax software, by mail, or through a tax professional. Filing the form does not require IRS approval — it is automatic if you submit it on time. However, if you miss the April 15 deadline without filing Form 4868, you lose the extension and face late-filing penalties.

Key Takeaways

  • An extended return is due October 15 of the same year, giving you six months past the April 15 deadline to file your actual return.
  • Form 4868 must be filed by April 15 to get the extension; filing it late means you do not receive the extension at all.
  • The extension covers filing only, not payment — taxes owed are still due April 15, and interest accrues on unpaid amounts after that date.
  • If you file Form 4868 but do not file your return by October 15, the IRS charges failure-to-file penalties in addition to any interest owed.

What happens if you file Form 4868 but miss the October 15 deadline

Once you have filed Form 4868, you have until October 15 to submit your actual tax return. If October 15 passes and your return is not filed, the IRS treats it as a late return and assesses a failure-to-file penalty. That penalty is typically 5 percent of the unpaid tax for each month or part of a month the return is late, up to 25 percent total. This penalty stacks on top of any interest owed on unpaid taxes.

The IRS does not send a warning or a second notice before charging the penalty. If your return arrives on October 16, you are subject to the penalty. The only exception is if you have a valid reason the IRS accepts — for example, you were out of the country for the entire extension period, or you had a serious illness. Even then, you must document the reason and submit it with your return or in a separate letter to the IRS.

When the October 15 deadline falls on a weekend or holiday

If October 15 falls on a Saturday or Sunday, the deadline moves to the next business day — usually Monday. If October 15 falls on a federal holiday, the deadline moves to the next day that is not a weekend or holiday. For example, if October 15 is a Saturday in a given year, your return is due Monday, October 17. The IRS publishes the exact deadline each year on its website and in tax forms.

If you mail your return, the postmark date is what counts, not the date it arrives at the IRS. A return postmarked on or before the deadline is considered on time, even if the IRS receives it weeks later. If you file electronically, the return must be transmitted by 11:59 p.m. Eastern Time on the deadline date.

Paying taxes owed before the October 15 deadline

Even though your return is not due until October 15, any taxes you owe are due April 15. If you do not pay by April 15, the IRS charges interest on the unpaid balance starting April 16. Interest accrues daily at a rate set quarterly — currently around 8 percent per year, though this changes. You also face a failure-to-pay penalty of 0.5 percent per month on unpaid taxes, up to 25 percent total.

You do not have to wait until you file your return to pay. Many people estimate what they owe, pay it by April 15, and then file their actual return by October 15. This stops interest and penalties from accruing. If you overpaid, you will receive a refund after you file. If you underpaid, you will owe interest on the difference, but only from April 15 forward, not from October 15.

States may have different extended deadlines

Most states follow the federal October 15 deadline if you file Form 4868 with the IRS. However, some states have their own extension rules and deadlines. A few states do not recognize federal extensions at all and require you to file a separate state extension form. You should check your state tax agency's website or contact them directly to confirm the deadline for your state return.

If you live in a state with income tax and file a federal extension, assume you need to file a state extension as well unless your state explicitly says otherwise. Some states allow you to file the state extension at the same time as the federal one; others require a separate form. Filing only the federal extension and missing your state deadline can result in state penalties and interest, even if you are on time federally.

Frequently Asked Questions

Does filing Form 4868 mean I do not have to pay taxes by April 15?

No. Form 4868 extends only the filing deadline, not the payment deadline. Taxes owed are still due April 15. If you do not pay by then, interest and penalties begin accruing immediately. You can file Form 4868 and pay what you estimate you owe by April 15 to avoid interest.

What if I file Form 4868 but then do not file my return by October 15?

The IRS charges a failure-to-file penalty of 5 percent per month on unpaid taxes, up to 25 percent. This penalty applies even if you filed Form 4868 on time. Interest also continues to accrue. The only way to avoid the penalty is to file before October 15 or show the IRS you had a valid reason for the delay.

Can I file Form 4868 after April 15?

No. Form 4868 must be filed by April 15 to receive the extension. If you miss that deadline, you do not get the six-month extension. You can still file your return late, but you will face failure-to-file penalties from the moment April 15 passes.

If I mail my return on October 15, is it on time?

Only if it is postmarked on or before October 15. The postmark date is what the IRS uses for mailed returns, not the arrival date. If you file electronically, the return must be submitted by 11:59 p.m. Eastern Time on October 15.

Do I need to file a separate extension with my state?

Most states follow the federal October 15 deadline, but some require a separate state extension form. Check your state tax agency's website to confirm. Filing only the federal extension and missing your state deadline can result in state penalties, even if you are on time federally.