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Critical Business Tax Deadlines for March 2026

While April 15 often dominates the public conversation regarding taxes, seasoned business owners know that March is the heavy lifter for pass-through entities and information reporting. As Enrolled Agents specializing in tax resolution, we often see that missed deadlines in March are the precursor to the IRS notices we help clients resolve later in the year.

For March 2026, the calendar is packed with obligations for S Corporations, Partnerships, and employers. Staying ahead of these dates is your best defense against failure-to-file penalties. Here is your roadmap for the month.

March 2: The Paper Filing & Information Deadline

If your business still relies on paper filing for information returns, the window closes early in the month. While the IRS strongly encourages electronic filing (which offers a later deadline), paper forms must be postmarked by this date to be considered timely.

Information Returns (1099 Series)
You must file government copies of Forms 1099 and the transmittal Form 1096 for payments made in 2025. Note that this applies to returns other than the 1099-NEC, which was due back in February.

Business owner reviewing tax deadlines on laptop

ACA Reporting for Large Employers
Applicable Large Employers (ALEs) filing paper forms must submit Forms 1094-C and 1095-C to the IRS. Providers of minimum essential coverage must file Forms 1094-B and 1095-B. If you opt to file these electronically, you gain an extension until March 31.

Farmers and Fishermen
If you did not pay your estimated tax by January 15, your 2025 income tax return (Form 1040) is due today to avoid penalties. If estimated payments were made on time, you have until April 15.

March 16: The Pass-Through Entity Deadline

This is arguably the most critical business tax deadline of the year for partnerships and S Corporations. Missing this date can result in substantial monthly penalties per partner or shareholder.

Partnerships (Form 1065)
Calendar year partnerships must file Form 1065 and provide each partner with their Schedule K-1 (and K-3 if applicable). If the return is not ready, you must file Form 7004 to request an automatic 6-month extension. Remember, an extension to file is not an extension to pay any state-level taxes that might be due.

S Corporations (Form 1120-S)
Calendar year S Corps must file Form 1120-S and distribute Schedule K-1s to shareholders. Similar to partnerships, if you cannot file a complete return by today, use Form 7004 to secure a 6-month extension. If the S Corp owes tax (which is rare but possible depending on the state or specific built-in gains), it must be paid by today to avoid interest.

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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. Filing late means the election generally won't take effect until 2027, unless specific relief provisions are met.

Bald Eagle representing federal tax compliance

March 31: Electronic Filing Deadline

The IRS continues to incentivize digital records by offering later deadlines for e-filing.

Electronic Information Returns
If you file electronically, March 31 is the deadline for Forms 1099, 1098, and W-2G. This is also the electronic filing deadline for the Affordable Care Act forms (1094/1095 series) and the Tip Income return (Form 8027).

Important Administrative Notes

Disaster Area Relief

The IRS frequently provides automatic extensions for businesses located in designated disaster areas. If you have been affected by severe weather, verify your status on the official government pages:

Weekend and Holiday Rule

As per standard IRS regulation, if a due date falls on a Saturday, Sunday, or legal holiday, the deadline is pushed to the next business day.

Facing IRS Issues?

At IRS Tax Pros, we understand that tax compliance can sometimes fall through the cracks. We don't handle daily bookkeeping—our expertise is solving the problems that arise when taxes go unresolved. If you have missed deadlines or are facing aggressive collection actions, contact us to discuss a resolution strategy.

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We solve tax problems for individuals and help tax pros solve tax problems for their clients.
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