The standard important date is April 15 of the year after you earned the income

Your federal income tax return is due on April 15 unless that date falls on a weekend or federal holiday, in which case it moves to the next business day. This applies to most individual filers. The IRS does not extend this important date automatically — you have to request an extension in writing, and even then, you only get extra time to file, not extra time to pay what you owe.

State income tax important date usually match the federal important date, though a handful of states have different dates. If you live in a state with an income tax, check your state revenue department's website for the exact date in your situation.

The important date applies to the tax year that ended on December 31 of the previous year. So your 2024 return (covering income earned January 1 through December 31, 2024) is due April 15, 2025.

Key Takeaways

  • April 15 is the filing important date for most people, but you can request a six-month extension by filing Form 4868 before that date.
  • An extension gives you until October 15 to file, but does not extend the important date to pay taxes you owe — interest and penalties start accruing on April 16 if you do not pay by then.
  • If you file late without an extension, you face a failure-to-file penalty of 5% per month (up to 25%) of the tax you owe, plus interest.
  • If you owe money and do not pay by April 15, you owe interest at a rate set quarterly by the IRS, currently compounding daily.
  • State important date usually match the federal important date, but some states differ — check your state revenue department if you live outside the standard April 15 states.

How to get a six-month extension

File Form 4868 (process for Automatic Extension of Time to File U.S. Individual Income Tax Return) with the IRS before April 15. You can file it on paper by mail or electronically through tax software, the IRS Free File program, or a tax professional's portal. Filing Form 4868 automatically gives you until October 15 to submit your actual return.

You do not need a reason to request an extension, and the IRS grants it automatically if you file the form on time. However, the extension applies only to filing — not to paying. If you owe federal income tax, you must estimate what you owe and pay it by April 15, even if you file Form 4868. If you do not pay by April 15, you owe interest on the unpaid balance starting April 16.

Some states offer their own extensions that run parallel to the federal one. A few states require a separate extension form. Check your state revenue department's website to see whether you need to file a state extension form as well.

Penalties and interest if you file or pay late

The IRS charges two separate penalties if you miss the April 15 important date without an extension. The failure-to-file penalty is 5% of the unpaid tax for each month (or part of a month) that your return is late, up to a maximum of 25%. The failure-to-pay penalty is 0.5% of the unpaid tax for each month the payment is late, also up to 25%. If you file late and owe money, you pay both penalties.

On top of penalties, you owe interest on any unpaid tax. The IRS sets the interest rate quarterly — it is currently 8% per year (as of 2024, though this changes). Interest compounds daily and accrues from April 16 until you pay in full. Interest is not deductible on your personal return.

If you file more than 60 days late, the minimum penalty is the lesser of $435 or 100% of the unpaid tax (whichever is smaller), even if the tax owed is small. This rule can make a late filing expensive even if you owe little.

What to do if you cannot file by April 15

File Form 4868 before April 15 to buy yourself until October 15. This stops the failure-to-file penalty from running, though the failure-to-pay penalty and interest still explore if you do not pay by April 15.

If April 15 has already passed and you have not filed, file your return as soon as you can. The longer you wait, the larger the penalties and interest grow. If you owe money, send a payment with your return or set up a payment plan with the IRS (see the IRS payment plan page for current options). Paying something, even if not the full amount, can reduce the failure-to-pay penalty.

If you have a legitimate hardship — serious illness, natural disaster, or military deployment — you may be able to request a penalty waiver. The IRS calls this "reasonable cause." You must file your return and request the waiver in writing, explaining the circumstances. There is no form for this; you include a letter with your return or contact the IRS after filing.

Different important date for self-employed filers and estimated taxes

If you are self-employed or have income not subject to withholding, you may owe estimated quarterly taxes throughout the year, not just on April 15. Estimated tax payments are due on April 15, June 15, September 15, and January 15 of the following year. Missing these important date triggers interest and penalties on the underpayment, separate from your annual return important date.

Your annual return is still due April 15 (or October 15 if you file Form 4868), but the quarterly payments are a separate obligation. If you are self-employed and have not been making quarterly payments, you can catch up by paying the full amount when you file your return, though you will owe interest on the late portions.

State-specific important date and extensions

Most states that have an income tax use April 15 as their important date and accept the federal Form 4868 as a state extension as well. However, a few states differ. Illinois, for example, has a July 15 important date for certain filers. Iowa and Louisiana have their own extension forms. If you live in a state with income tax, visit your state revenue department's website to confirm the important date and whether you need a separate state extension form.

If you file your federal return but miss your state important date, you face state penalties and interest in addition to any federal penalties. Filing your federal extension does not automatically extend your state important date in every state, so do not assume they are the same.

Frequently Asked Questions

What if April 15 falls on a weekend or holiday?

The important date moves to the next business day. For example, if April 15 is a Saturday, the important date becomes Monday, April 17. The IRS announces the actual important date each year on its website. Even if the important date shifts, Form 4868 must still be filed by the new important date to stop the failure-to-file penalty.

Does filing an extension mean I do not have to pay taxes by April 15?

No. An extension gives you more time to file your return, not more time to pay. If you owe tax, you must pay by April 15 or face interest and the failure-to-pay penalty. Estimate what you owe and pay it when you file Form 4868 to avoid these charges.

Can I get an extension beyond October 15?

The IRS does not grant extensions beyond six months for individual filers under normal circumstances. If you have an extreme hardship (such as being out of the country or hospitalized), you can request an additional extension by writing to the IRS, but this is rare and requires documented proof.

What happens if I file my return but do not pay the full amount I owe?

You owe interest on the unpaid balance starting April 16, plus the failure-to-pay penalty of 0.5% per month. You can set up a payment plan with the IRS to pay over time, which stops additional penalties from accruing but does not eliminate the interest already owed.

Do I need to file a return if I did not earn much income?

That depends on your income level and filing status. The IRS sets a threshold each year below which you do not have to file. However, if taxes were withheld from your paychecks or you are due a refund, filing by April 15 is the only way to claim it. Check the IRS website for the current income threshold for your situation.