Miss a corporate filing deadline and the meter starts that day: 5% of unpaid tax per month for the return itself, plus $245 per shareholder per month for S-corps and partnerships. Set a reminder weeks ahead and the whole problem disappears.
Done in seconds. No sign-up required.
Real penalty math from IRS published rates, not estimates.
of unpaid tax added each month a return is late, up to a 25% ceiling
IRS failure-to-file penalty, IRC §6651
per shareholder, per month for late S-corp and partnership returns, charged for up to 12 months
IRS 2025 indexed amount, Rev. Proc. 2024-40
minimum first-year exposure for a single-shareholder S-corp that files one year late
$245 × 12 months, before tax penalties
Corporate filing happens once a year, sometimes once a quarter for estimated payments, and the date is not where most small business owners live their attention. You are running the company. The deadline sits on a calendar somewhere, vaguely, until the week of, and by then your CPA is already booked solid and your records are not ready.
The other trap is the extension. You file Form 7004 in March, get six more months, and the new date feels far enough away that it falls off your radar. September arrives. Then October. The IRS does not email you. Your accountant might or might not chase you. The first reminder that the deadline existed is the CP162 notice with the penalty already on it.
A simple reminder set 60 days out closes the gap. Long enough to gather K-1 information, reconcile books, and get on your accountant's schedule before the rush.
Most calendar reminders fire once and disappear. That is fine for a meeting. It is not fine for a deadline that costs $245 per shareholder per month if you miss it. A good corporate tax reminder works in stages, each one tied to a specific action you can take.
Gather records, request K-1 source data, reconcile the year-end books. Book your accountant before they hit capacity.
Final review, missing-document chase, decide whether to file Form 7004 for an extension if needed.
If you do not mark the return as filed, BoldRemind keeps emailing. No quiet disappearance, no missed deadline because of one ignored notification.
| S-corp / partnership deadline | March 16, 2026 (15th if not a weekend) |
| C-corp deadline | April 15, 2026 |
| Extension form | Form 7004, due by original deadline |
| Extended S-corp / partnership deadline | September 15, 2026 |
| Extended C-corp deadline | October 15, 2026 |
| Failure-to-file penalty | 5% of unpaid tax per month, up to 25% |
| Failure-to-pay penalty | 0.5% per month, applied separately |
| S-corp / partnership per-shareholder penalty | $245 per month, up to 12 months |
Three problems that come up in nearly every late return.
March 16 in 2026 because the 15th falls on a Sunday. Last year it was the 17th. Every year shifts slightly with weekends and federal holidays.
See the exact 2026 date →LLC, S-corp, C-corp, partnership all have different deadlines and different forms. The wrong assumption costs you a month of penalties.
Deadlines by entity type →Failure-to-file, failure-to-pay, per-shareholder penalty, and interest all run at the same time. A small late filing turns into thousands within months.
Penalty breakdown →Everything else about corporate tax deadlines — the details live here.
For calendar-year filers in 2026, S-corporations (Form 1120-S) and partnerships (Form 1065) are due March 16. C-corporations (Form 1120) are due April 15. Fiscal-year corporations file by the 15th day of the fourth month after their year-end. See the full year-specific breakdown on the 2026 deadline page.
The IRS failure-to-file penalty is 5% of unpaid tax per month, capped at 25%. S-corporations and partnerships face a separate per-shareholder or per-partner penalty: $245 per month for each shareholder, for up to 12 months. A late return with three shareholders runs $735 per month before any tax is even owed.
Set the first reminder 60 days out so you have time to gather records and work with your accountant without rushing. A second reminder 30 days before the deadline and a final one a week out covers the common "I meant to do it" gap. BoldRemind keeps emailing follow-ups until you mark the return as filed.
No. The IRS publishes the calendar but does not email business owners ahead of the deadline. Notices arrive only after a return is late, when penalties have already started. Any pre-deadline reminder has to come from you, your accountant, or a tool like BoldRemind.
Yes, and arguably more. The extension pushes the filing date to September 15 (S-corp, partnership) or October 15 (C-corp), but the tax payment was still due on the original deadline. Most missed-extension cases happen because the new date feels far away and gets forgotten over the summer.
C-corporations file Form 1120. S-corporations file Form 1120-S plus Schedule K-1 for each shareholder. Partnerships and multi-member LLCs taxed as partnerships file Form 1065 plus Schedule K-1 for each partner. Single-member LLCs are disregarded and file on the owner's Schedule C.
Sometimes. First-time penalty abatement waives the failure-to-file penalty if you have a clean compliance history for the prior three years. Reasonable-cause relief applies if you can document a genuine reason (illness, disaster, inability to obtain records). Forgetting the date does not qualify.
Free. No account. Takes 30 seconds. Get an email 60, 30, and 7 days before your deadline — and follow-ups until the return is filed.
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