Your Business Tax Calendar: Important Deadlines for March 2026

If you felt a sigh of relief after the January 31st deadlines, it is time to refocus. March is arguably one of the heaviest lifting months for business taxation, specifically for flow-through entities and employers. From finalizing S Corporation returns to managing ACA reporting, keeping track of these dates is vital to avoiding penalties and keeping your books in good standing.

Here is your breakdown of the critical compliance dates for March 2026.

March 2: The Paper Filing & Special Industry Deadline

While electronic filing has become the standard, the IRS still maintains specific earlier deadlines for paper filings. Because March 1 falls on a Sunday this year, these deadlines move to Monday, March 2.

Information Returns (Paper Filing)

If you are still filing hard copies of your information returns, this is your deadline for filing the government copies of Forms 1099 (excluding the 1099-NEC, which was due earlier) and transmittal Forms 1096. This applies to various payments made in 2025.

Similarly, Payers of Gambling Winnings filing on paper must submit Form 1096 and Copy A of all Forms W-2G issued for 2025. Note that if you file these electronically, you have until the end of the month.

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ACA Reporting (Paper Filing)

For Applicable Large Employers (ALEs) and other providers of minimum essential coverage filing on paper:

  • ALEs: File Forms 1094-C and 1095-C.
  • Other Providers: File Forms 1094-B and 1095-B.

As with the other forms mentioned, switching to electronic filing grants you an automatic extension until March 31. Additionally, this is the deadline to provide the recipient copies of Form 1095-C (for ALEs) and Form 1095-B to responsible individuals.

Farmers and Fishermen

If you did not pay your 2025 estimated tax by January 15, 2026, you must file your 2025 income tax return (Form 1040 or 1040-SR) and pay the full tax due by this date to avoid penalties.

March 16: The Big Deadline for Partnerships & S Corps

Because the standard March 15 deadline falls on a Sunday, the due date for calendar year partnerships and S Corporations shifts to Monday, March 16. This is often considered the "Super Bowl" of business tax season.

Partnerships (Form 1065)

You must file the 2025 calendar year return (Form 1065) and provide each partner with their Schedule K-1 and, if applicable, Schedule K-3. These schedules are critical for your partners, as they cannot file their personal returns until they receive them.

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Need more time? You can file Form 7004 to request an automatic 6-month extension. If you extend, the return and Schedule K-1s will be due September 15.

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S Corporations (Form 1120-S)

Calendar year S Corps must file Form 1120-S and pay any tax due. Similar to partnerships, you must provide each shareholder with their Schedule K-1 and Schedule K-3.

If you cannot file by this date, file Form 7004 for a 6-month extension. However, please remember: an extension to file is not an extension to pay. You must estimate and pay any tax owed by March 16 to avoid interest and penalties.

S Corporation Election (Form 2553)

If you operate an LLC or C Corp and want to be taxed as an S Corp for the calendar year 2026, you must file Form 2553 by this date. Missing this window generally means your S Corp status won't take effect until 2027, potentially costing you significant tax savings.

March 31: Electronic Filing Deadline

For businesses that utilize accounting software or payroll providers to e-file, the end of the month marks the final cutoff for several information returns.

  • Forms 1099 and W-2G: This is the electronic filing due date for 1099s (other than 1099-NEC) and gambling winnings forms.
  • ACA Forms: Electronic filing of Forms 1094-C, 1095-C, 1094-B, and 1095-B is due.
  • Tip Reporting: Large Food and Beverage Establishment Employers must electronically file Form 8027.

Disaster Area Extensions

In certain cases, businesses located in federally declared disaster areas may be granted additional time to file and pay. We monitor these announcements closely. To verify if your area is affected, you can check the FEMA declarations or the IRS disaster relief page.

Navigating March deadlines can be complex, especially with the interplay between flow-through returns and personal filings. If you need assistance with an extension or finalizing your K-1s, please reach out to us immediately so we can ensure you stay compliant.

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If any of these topics caught your attention, please contact to start the conversation!
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