Critical Business Tax Deadlines for March 2026

While January and February are often spent gathering documents, March is when the tax season truly intensifies for business owners. For many of our clients—particularly partnerships and S Corporations—this month brings the first major filing deadlines of the year. Ensuring these dates are met is essential to avoiding costly late-filing penalties.

Here is your roadmap for March 2026 business compliance.

March 2: The Paper Filing & Special Industry Deadline

Because the standard March 1 deadline falls on a Sunday this year, several due dates roll over to Monday, March 2. This date primarily affects businesses that still file paper returns or operate in specific industries like agriculture.

Information Returns (Paper Filers)

If you have not yet transitioned to electronic filing, March 2 is the deadline to file government copies of information returns for payments made in 2025. This includes:

  • Form 1096 and Forms 1099: For miscellaneous payments (excluding the 1099-NEC, which was due previously).
  • Gambling Winnings: Form 1096 along with Copy A of Forms W-2G.

ACA Reporting for Large Employers

Applicable Large Employers (ALEs) filing on paper must submit Forms 1094-C and 1095-C regarding health insurance offers and coverage. Other providers of minimum essential coverage must file Forms 1094-B and 1095-B. While we generally encourage e-filing (which grants you until March 31), paper filers must act by this date.

Farmers and Fishermen

If you did not pay your estimated taxes by January 15, your 2025 income tax return (Form 1040 or 1040-SR) is due now. Filing by this date allows you to avoid an estimated tax penalty.

Close up of sticky notes on a calendar planning tax deadlines

March 16: Pass-Through Entities & S Corp Elections

This is arguably the most critical date of the month for small to mid-sized businesses. Since March 15 is a Sunday, the deadline moves to Monday, March 16.

Partnerships (Form 1065)

Partnerships must file their 2025 calendar year return or request an automatic 6-month extension using Form 7004. You must also provide each partner with their Schedule K-1 (and Schedule K-3 if applicable). Remember, partners generally cannot file their personal returns until they receive these schedules.

S Corporations (Form 1120-S)

S Corps must file their 2025 income tax return and pay any tax due. Similar to partnerships, if you need more time to ensure your books are accurate, file Form 7004 for an extension. You must provide shareholders with their Schedule K-1 so they can manage their personal filings.

Note: An extension to file is not an extension to pay. If your S Corp owes tax, estimated payments should be made with the extension to avoid interest.

S Corporation Election (Form 2553)

If you operate an LLC or C Corp and wish to be taxed as an S Corp for the 2026 tax year, you must file Form 2553 by this date. Missing this window generally means waiting until the 2027 tax year for the election to take effect.

Business woman working on laptop reviewing financial documents

March 31: Electronic Filing Deadline

The IRS strongly incentivizes electronic filing by granting a later deadline. March 31 is the final due date for electronically filing:

  • Forms 1099, 1098, and W-2G (with the IRS).
  • ACA Forms: 1094-C, 1095-C, 1094-B, and 1095-B.
  • Tip Reporting: Form 8027 for large food and beverage establishments.

Other Recurring Deadlines

March 16 is also the due date for monthly payroll depositors (depositing tax for February payments) and non-payroll withholding deposits.

Disaster Area Relief

The IRS frequently offers extended deadlines for businesses located in designated disaster areas. If your business has been impacted by severe weather, please check the FEMA and IRS disaster relief pages to see if you qualify for automatic extensions.

Need Help with Extensions?

Whether you need to file an extension for your partnership or need assistance preparing complex K-1s, prompt action is required to stay compliant. Contact Virginia Gibbs at Tax Lady 1040 today to ensure your business filings are handled with professional care.

Share this article...

Want our best tax and accounting tips and insights delivered to your inbox?

Sign up for our newsletter.

I confirm this is a service inquiry and not an advertising message or solicitation. By clicking “Submit”, I acknowledge and agree to the creation of an account and to the and .
Tax Lady 1040 We love to chat
Please feel free to use our Ai powered chat assistant. Or use the buttons below to contact us.
Please fill out the form and our team will get back to you shortly The form was sent successfully