Extended S corp and partnership returns were due September 15. If yours didn't go out, the penalty meter is already on — here's how to stop it, and how first-time abatement can wipe it entirely.
Extended 2025 returns for S corporations (Form 1120-S) and partnerships (Form 1065) were due September 15. If yours is still unfiled, here's the honest picture — and the playbook that usually makes most of the damage go away.
The late-filing penalty for these returns is $255 per owner, per month, for up to 12 months — and any part of a month counts as a full month. A two-partner LLC that files in late September owes $510. Wait until December and it's $2,040. Ten partners? Multiply everything by five. This penalty applies even if the business owes zero tax, because these are pass-through returns — the IRS charges for the late information, not late money.
Every month you wait adds another $255 per owner. If the bookkeeping is behind, that's a solvable problem measured in days — we do catch-up cleanups constantly. The math almost never favors waiting.
The most under-used relief in the tax code: if the business filed and paid on time for the previous three years and has no other open issues, the IRS routinely removes this penalty on request. It's called first-time penalty abatement, it's administrative (no sob story required), and it can be requested with a phone call or a short letter once the penalty notice arrives. We request it as a standard step for clients in this spot.
A late 1065 or 1120-S means late K-1s, and the owners' personal extended returns are due October 15. Don't let one late business return cascade into several late personal ones — that's where the 5%-per-month personal penalties start stacking.
If any of this is your situation, forward us the notice and the current state of the books. Stopping the clock this week is usually worth thousands.
Talk it through with a licensed US tax professional — we'll tell you honestly whether it applies to your situation.
Extended 2025 returns are due October 15 — and there is no second extension. Here is the three-week game plan, what missing it actually costs, and what to do if you can't pay.
Extended 1120-S and 1065 returns are due September 15, 2026 — and the late-filing penalty is $255 per owner, per month, even at $0 tax. What it costs, how abatement works, and the same-day Q3 estimate everyone forgets.
The extension deadline is October 15, 2026 — and 2025 returns are the first under the new tax law. New deductions for tips, overtime, seniors, SALT, and car loans apply retroactively, and the late-filing penalty is 10x the late-payment one.
