March 2026 Business Tax Calendar: Deadlines for Partnerships and S-Corps

While February is often dominated by W-2s and early payroll reports, March is when the tax season truly shifts gears for business owners. If you operate a pass-through entity like an S Corporation or a Partnership, this is your primary filing month.

We know the calendar can feel crowded right now. To help you prioritize, we have broken down the critical compliance dates for March 2026 below. Keeping these deadlines in clear view helps avoid penalties and keeps your financial house in order.

Office calendar and calculator

March 2: The Information Return Cutoff (Paper Filers)

If your business still handles filings via traditional mail rather than electronically, the first business day of the month is a major deadline. However, please note that if you file these forms electronically, you generally have until March 31 (see below).

  • Forms 1099 and 1096: You must file government copies of information returns (Forms 1099) and the transmittal Form 1096 for payments made in 2025. Note: This does not apply to 1099-NEC forms, which were due back in February.
  • Gambling Winnings: Casinos and similar venues must file Form 1096 and Copy A of all Forms W-2G issued for 2025.
  • ACA Reporting (ALE): Applicable Large Employers must file paper Forms 1094-C and 1095-C. All other providers of minimum essential coverage must file paper Forms 1094-B and 1095-B.
  • Tip Reporting: Large food and beverage establishments filing on paper must submit Form 8027 (and 8027-T if applicable) to report tip income.

Farmers and Fishermen

For our clients in the agriculture and fishing industries: March 2 is the due date to file your 2025 income tax return (Form 1040) and pay any tax due, unless you paid your estimated tax by January 15, in which case you have until April 15.

March 16: The Pass-Through Entity Deadline

This is arguably the most significant date in March for small business owners. If you run a Partnership or an S Corp, the IRS requires your return (or an extension request) by this date. This timeline ensures that partners and shareholders receive their Schedule K-1s in time to file their personal returns in April.

Partnerships (Form 1065)

You must file the 2025 calendar year return (Form 1065). More importantly, you need to provide each partner with their Schedule K-1 (and Schedule K-3 if applicable). If you cannot file a complete return by this date, we must file Form 7004 to request an automatic 6-month extension.

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S Corporations (Form 1120-S)

Similar to partnerships, S Corps must file the 2025 calendar year income tax return (Form 1120-S) and pay any tax due. You must also issue Schedule K-1s to your shareholders so they can report that income on their personal filings. If you need more time to file the paperwork, filing Form 7004 grants an extension, but remember: an extension to file is not an extension to pay. Estimated taxes owed must be paid by this date to avoid interest.

Electing S Corp Status (Form 2553)

Are you an LLC or Corporation looking to be taxed as an S Corp for the 2026 tax year? You must file Form 2553 by March 16. Filing this election late means the status generally won't take effect until the 2027 tax year.

Tax forms and pen

March 31: Electronic Filing Deadline

The IRS encourages electronic filing by offering a later due date. If you e-file, March 31 is your deadline for:

  • Forms 1099 (excluding 1099-NEC)
  • Forms W-2G
  • ACA Forms (1094-B/C and 1095-B/C)
  • Form 8027 (Tip Income)

Routine Payments and Reminders

March 16: Payroll & Non-Payroll Deposits
If you are on a monthly deposit schedule, your tax deposits for payments made in February are due.

Disaster Area Relief
The IRS frequently adjusts deadlines for businesses located in designated disaster areas. If you have been affected by severe weather events, your dates may differ. You can verify your status at the following links:

We Are Here to Help

March involves a lot of moving parts, specifically regarding K-1s and entity elections. If you are worried about getting your data together for the S Corp deadline, or if you are unsure if you should file an extension, please reach out. We can walk you through it step by step to ensure you stay compliant without the stress.

Virtual AI
If you’re ready to get a handle on your tax situation, reach out and we’ll guide you through each step.
Let’s Sort This Out
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