IRS Urges Extension Filers Not to Wait Until October 15

The IRS said on August 26, 2026, in IR-2026-101 that taxpayers who requested a filing extension for their 2025 return should submit it as soon as they can rather than waiting for the October 15 deadline. The reminder is routine, the IRS issues a version of it most years, but the underlying math is worth revisiting for high earners with complex returns, since an extension only postpones the paperwork, not the tax bill.

What changed

The IRS notice reiterated that IRS Free File remains open through October 15, 2026, offering guided tax preparation to taxpayers with 2025 adjusted gross income of $89,000 or less, with Free File Fillable Forms available above that threshold for anyone comfortable preparing their own return. The agency's practical case for filing early is that it avoids the October crush, when phone lines, software support, and preparer availability are all stretched thinnest, and it leaves more time to resolve any issues, math errors, missing forms, or payment arrangements, before the hard deadline.

Who is affected

Extension filers are disproportionately higher-income taxpayers: partners and S corporation shareholders waiting on late K-1s, business owners finalizing complex books, and households with equity compensation, multi-state income, or investment activity that takes longer to reconcile. Many of these filers also carry an unpaid balance from April, since an extension to file is not an extension to pay, and that gap is where the deadline reminder has real teeth.

Why the IRS keeps repeating this reminder

The IRS issues a version of this notice most years because the confusion it addresses is persistent: taxpayers conflate an extension to file with an extension to pay, and only discover the difference when a penalty notice arrives months later. An extension grants an automatic six months to submit the paperwork itself, filed by the original April deadline, but any tax owed was still due in April, with interest and the failure-to-pay penalty running from that date regardless of the extension. Filing the actual return early does not erase penalties that already started accruing in the spring, but it stops the much larger failure-to-file penalty from ever starting, and it surfaces any balance due while there is still time to arrange payment before October.

The after-tax math

The penalty structure punishes filing late far more than paying late. The failure-to-file penalty runs 5% of the unpaid tax for each month or partial month a return is late, capped at 25%, while the failure-to-pay penalty is a much smaller 0.5% per month, also capped at 25%. Both accrue on top of underpayment interest that has been running at 7% for individuals through 2026. Example: a couple with a $50,000 balance who filed for an extension but then also missed the October 15 filing deadline by two months would owe roughly $5,000 in failure-to-file penalties alone, ten times the roughly $500 they would owe in failure-to-pay penalties for the same period, plus ongoing interest on the unpaid balance from the original April due date.

Moves to discuss with your advisor

Households still waiting on K-1s or other late documents should ask their CPA whether enough information exists to file a reasonably accurate return now, with an amendment later if a small K-1 adjustment comes in, rather than waiting on every last document and risking the October 15 cutoff. Anyone carrying an unpaid balance from the original April deadline should discuss paying it down as soon as possible regardless of when the return itself gets filed, since failure-to-pay penalties and interest are running on the balance every month.

What to watch

October 15 is a hard deadline with no further extension available for individual filers absent a federally declared disaster area, so taxpayers who miss it face the full failure-to-file penalty on top of whatever they already owe. The IRS has also flagged that phone and processing wait times typically spike in the two weeks before the deadline, another reason the agency is pushing early filing this year.

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