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

March is when tax season truly shifts into high gear for the business world. While many individuals are still gathering documents for April, pass-through entities and employers face a series of critical compliance hurdles this month. Because March 15 falls on a Sunday in 2026, several major deadlines have pushed to Monday, March 16.

Whether you are finalizing your partnership return or wrapping up information reporting, missing these dates can lead to costly penalties. Here is your essential guide to the March 2026 business tax calendar.

March 2: The Paper Filing Deadline

If your business still files paper information returns, this is your cutoff. While the IRS has lowered the threshold requiring electronic filing, smaller entities filing on paper must adhere to this earlier deadline. Since February 28 fell on a weekend, you have until today.

Information Returns (Forms 1099 & 1096)

File government copies of Form 1096 and standard information returns (Forms 1099) for payments made in 2025. Note that this applies to forms other than the 1099-NEC, which was due back in roughly a month ago.

Gambling Winnings & ACA Reporting

If you are a payer of gambling winnings, file Form 1096 along with Copy A of all Forms W-2G. Additionally, Applicable Large Employers (ALEs) filing paper Forms 1094-C and 1095-C regarding health coverage must submit them now. This also applies to other providers filing Forms 1094-B and 1095-B.

Farmers and Fishermen

For those in the agriculture or fishing industries who did not pay estimated taxes by January 15, your 2025 income tax return (Form 1040) and tax payment are due today to avoid penalties.

Team reviewing business tax deadlines in a virtual meeting

March 16: The Big Date for Pass-Through Entities

This is arguably the most stressful day of the month for many business owners. If you operate as a partnership or S Corporation, your tax returns (or extension requests) are due.

Partnerships (Form 1065)

You must file the 2025 Form 1065 and provide each partner with their Schedule K-1. The K-1 is essential for your partners, as they generally cannot file their personal returns until they receive it. If you need more time to ensure accuracy, file Form 7004 to request an automatic 6-month extension. This pushes the filing deadline to September 15.

S Corporations (Form 1120-S)

Similar to partnerships, S Corps must file Form 1120-S and pay any tax due by this date. Shareholders need their Schedule K-1s to complete their individual filings. If the books aren't quite ready—perhaps you are waiting on corrections to the balance sheet—file Form 7004 and pay any estimated tax owed to secure an extension until September 15.

S Corporation Election for 2026

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

March 31: Electronic Filing Deadline

For businesses that file information returns electronically, you have until the end of the month to submit your data to the IRS.

  • Forms 1099, 1098, and W-2G: This is the final electronic filing due date.
  • ACA Forms: ALEs filing electronically must submit Forms 1094-C, 1095-C, 1094-B, and 1095-B by today.
  • Tip Income: Large food and beverage establishments filing Form 8027 electronically must also meet this deadline.
Analyzing financial statistics and tax data

Extensions and Next Steps

Remember that filing an extension for your business return provides more time to file the paperwork, not more time to pay any tax due. If a deadline falls on a weekend or legal holiday, it automatically moves to the next business day.

Tax season is a marathon, not a sprint. If you are feeling the pressure of the March deadlines or need help calculating an extension payment, please reach out to our office immediately. We are here to help you navigate these dates without the stress.

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