October 15 is the end of the road for an extended Form 1040. The 2025 returns extended in April 2026 are due October 15, 2026. The 2026 returns extended in April 2027 are due October 15, 2027. There is no further extension for individuals, and the IRS does not grant one on request.
What happens if you miss it
The failure-to-file penalty is computed from the original April due date, not from October. Miss October 15 and the clock reads as if you never extended: 5 percent per month from April, capped at 25 percent. If you owed $8,000, that cap is $2,000 before interest.
What is still open
- Payment plans. You can set one up any time.
- Penalty relief. First-time abatement and reasonable cause both still apply to a late return.
- The return itself. File it. A late return stops the failure-to-file penalty from growing and starts the statute of limitations, which never starts on a return you did not file.
Retirement contributions
This is the one deadline an extension actually moves. SEP IRA and solo 401(k) employer contributions for the prior year can be made up to the extended due date if you extended. Traditional and Roth IRA contributions cannot; those closed in April.
Common mistake
Assuming the extension moved the payment. Anything unpaid since April has been accruing interest and the failure-to-pay penalty the whole time.