The filing deadline depends on how your business is structured. Different entity types have different due dates, and missing yours can trigger penalties even if you don’t owe any tax.

Partnerships and S-corporations file by March 15. These are pass-through entities, meaning the business itself doesn’t pay income tax. Instead, it issues K-1s to each owner, who then reports that income on their personal return. The March 15 deadline exists so owners receive their K-1s in time to file personal returns by April 15.

C-corporations file by April 15 for calendar year filers. If your corporation uses a fiscal year, the return is due the 15th day of the fourth month after your fiscal year ends.

Sole proprietors and single-member LLCs report business income on Schedule C as part of their personal tax return, which is also due April 15.

If you need more time, you can file an extension. Partnerships and S-corps get a 6-month extension that pushes the deadline to September 15. C-corps also get 6 months, extending to October 15. Personal returns, including sole proprietors, extend to October 15 as well. But an extension gives you more time to file, not more time to pay. If you owe taxes, you still need to estimate and pay by the original deadline. Interest and penalties start accruing on any unpaid balance from that original date regardless of whether you filed an extension.

Don’t overlook estimated quarterly taxes. If you expect to owe $1,000 or more in federal tax for the year, the IRS expects you to pay throughout the year rather than in one lump sum. Quarterly estimated payments are due April 15, June 15, September 15, and January 15 of the following year. Missing these can trigger underpayment penalties even if you settle everything by the filing deadline. A good business tax return preparer will help you calculate these estimates so you avoid surprises.

One thing that catches Nashville-area business owners off guard is Tennessee’s franchise and excise tax. Tennessee doesn’t tax personal income, but businesses organized as corporations, LLCs, or partnerships may still owe this state business tax. That return is due the 15th day of the fourth month after your fiscal year ends, which is April 15 for calendar year filers. “No state income tax” does not mean “no state business tax filing.”

The best way to avoid scrambling at any of these deadlines is keeping your books accurate and current throughout the year. When your records are already clean, preparing the return is a straightforward process. When they’re not, you end up paying for bookkeeping services to catch up under time pressure, which costs more and creates unnecessary stress. Build the habit of staying current monthly so tax season is just another task on the calendar rather than an emergency.