S-Corporation tax returns are due on the 15th day of the third month after your fiscal year ends. For most businesses operating on a calendar year, that means March 15th. If the due date falls on a weekend or holiday, the deadline shifts to the next business day.

The March 15 deadline exists for a reason. S-Corps are pass-through entities, so the company itself doesn’t pay income tax. Instead, profits and losses flow through to shareholders via Schedule K-1. Those shareholders need their K-1s to complete their personal tax returns, which are due April 15. The one-month gap gives shareholders time to incorporate the S-Corp information into their individual filings.

You can request an automatic six-month extension by filing Form 7004 before the March 15 deadline. This moves your filing deadline to September 15. The extension is automatic, meaning the IRS grants it as long as you submit the form on time. However, an extension to file is not an extension to pay. If your S-Corp owes any taxes, perhaps from built-in gains or excess passive income, those amounts are still due March 15.

Late filing penalties for S-Corps are steep. The IRS charges $220 per shareholder for each month or partial month the return is late, up to 12 months. An S-Corp with three shareholders that files two months late owes $1,320 in penalties before any interest on unpaid taxes. This penalty applies even if no tax is due on the return itself.

Most S-Corps file extensions because gathering all the information needed for an accurate return takes time. There’s nothing wrong with extending as long as you actually file by September 15. What gets businesses in trouble is extending and then forgetting about the deadline entirely.

Business tax return preparation typically starts in January for calendar-year S-Corps. Your accountant needs time to review the prior year’s books, identify any adjustments, and prepare the return with enough lead time to address questions before the deadline.

If you have an internal bookkeeping team, make sure your financials are closed and reconciled by early February at the latest. Premium business accounting in Boca Raton includes the kind of month-end close discipline that makes tax season manageable rather than chaotic. Clean books throughout the year mean fewer surprises when it’s time to file.

State filing deadlines generally follow federal deadlines, but Florida S-Corps don’t file a separate state income tax return since Florida has no personal income tax. You may still have other state obligations depending on where you do business or where your shareholders reside.