10/15/2026
For anyone who filed an extension, today the last date to file a return before the failure-to-file penalty comes back into play.
Here's what changes if you don't file today.
โ A failure-to-file penalty starts running at 5% of the unpaid tax for each month or partial month, up to a 25% cap.
โ For any month where the failure-to-pay penalty also applies, the failure-to-file penalty drops to 4.5%.
โ Once a return is more than 60 days late, a minimum penalty applies: the lesser of $525 or the full amount owed.
The failure-to-pay penalty and interest already started running back on April 15, since an extension applies only to filing, not payment.
Filing late is still better than not filing. The failure-to-file penalty stops the day a return goes in, even if the balance isn't paid in full.
Outside of military deployment or a federally declared disaster, October 15 is the final extension available.
