Deadlines · calculator
Tax extensions: October 15 and what it does not move
The automatic six-month extension gives more time to file, never more time to pay.
Cost of filing or paying late
Penalties and interest
$260
On $4,000 unpaid for 6 months
- Failure-to-file penalty$0
- Failure-to-pay penalty$120
- Interest at 7% a year, compounded daily$140
An extension moves the filing date, not the payment date. Interest uses the current quarterly rate for the whole period; the IRS applies each quarter’s rate.
If you requested an extension for your 2025 return, it is due October 15, 2026: the automatic six-month extension moves the filing deadline from April 15, 2026 to that date, according to the IRS. For the 2026 return, the same request made by April 15, 2027 pushes filing to October 15, 2027. There are three ways to get it: pay part or all of the tax online and check the box saying the payment is for an extension, request it through IRS Free File (no income limit for extensions), or file Form 4868 by mail or electronically. The extension covers the return only. Tax not paid by April accrues interest and a failure-to-pay penalty of 0.5% a month, but you avoid the much larger failure-to-file penalty of 5% a month. Someone who owed $5,000 on the 2025 return, filed by October 15, 2026 under extension and pays six months late owes about $150 of penalty plus $179 of interest; without an extension, the penalties alone would reach $1,275. US citizens living abroad get an automatic two-month extension.
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Extension dates for both returns
| Return | Normal due date | Extension request by | Extended due date |
|---|---|---|---|
| Tax year 2025 | April 15, 2026 | April 15, 2026 | October 15, 2026 |
| Tax year 2026 | April 15, 2027 | April 15, 2027 | October 15, 2027 |
What an extension changes, and what it does not
It moves the date your return is due, so no failure-to-file penalty applies if you file by the extended date. It does not move the payment date, so interest at the quarterly rate, 7% a year in the last quarter of 2026, and the 0.5% monthly failure-to-pay penalty run on any balance from April. It does not extend the deadline for 2026 IRA contributions, which closes on April 15, 2027 regardless; SEP and solo 401(k) employer contributions, by contrast, can generally wait until the extended due date. It does not delay a refund claim, but nothing is refunded before the return is filed.
When an extension is worth it
Waiting for a corrected Form 1099 or a Schedule K-1 from a partnership, sorting out records after a move or an illness, or making sure a new deduction is claimed correctly are all good reasons. The Schedule 1-A deductions for tips and overtime, for instance, rely on records that some employers did not provide separately for 2025. If you owe, pay your best estimate in April and file once the numbers are right. The deadline page lists the other dates of the year, and the interest rate page computes interest on a balance.
After October 15
A return still not filed after the extended date is late from the original April due date: the failure-to-file penalty is computed from April, not from October, and the minimum penalty for a return more than 60 days late applies. If you cannot finish by then, file with the information you have and amend later; a return filed on time and corrected afterwards costs far less than a late one.
Abroad and in disaster areas
US citizens and resident aliens living outside the United States on the regular due date get an automatic two-month extension, to mid-June, and can request more time with Form 4868. Taxpayers in areas covered by an IRS disaster declaration often receive later deadlines for both filing and payment, announced area by area.
Sources: IRS: Get an extension to file your tax return (October 15); IRS: When to file (April 15, 2026 due date, automatic six-month extension); IRS: Failure to pay penalty; IRS: Quarterly interest rates on underpayments and overpayments, read on October 11, 2026.