For business owners, fiduciaries, and family offices, March is a pivotal month in the tax calendar. While January and February focus on gathering data, March is when significant filings for flow-through entities—Partnerships and S Corporations—come due. These filings are the cornerstone of compliance for high-net-worth individuals, as they generate the Schedule K-1s necessary for personal returns.

At Sullivan & Company CPA Inc., we believe that meeting these deadlines is not just about checking a box; it is about maintaining the integrity of your entity structures and avoiding unnecessary penalties. Below is a guide to the key dates and requirements for March 2026.

March 2: Information Reporting & Special Filings

While the primary deadline for 1099-NEC forms passed in early February, March 2 remains a critical date for other information returns. Accurate reporting here is essential for maintaining clean audit trails.

General Information Returns (Forms 1099 & 1096)

If you filed paper forms for payments made in 2025 (excluding the 1099-NEC), you must file the government copies of Forms 1099 along with the transmittal Form 1096 by this date.

ACA Reporting for Applicable Large Employers (ALE)

Employers classified as ALEs must file paper Forms 1094-C and 1095-C with the IRS. Non-ALE providers of minimum essential coverage must file paper Forms 1094-B and 1095-B. Note that if you are filing electronically—which is often recommended for efficiency and security—the deadline extends to March 31.

Specific Industry Filings

• Payers of Gambling Winnings: File Form 1096 and Copy A of Forms W-2G.
• Large Food and Beverage Establishments: File Form 8027 (Tip Income) and Form 8027-T if filing by paper.
• Farmers and Fishermen: File your 2025 income tax return (Form 1040) and pay any tax due, unless you paid your estimated tax by January 15, 2026 (in which case you have until April 15).

March 2: Furnishing Health Coverage Forms

Applicable Large Employers must provide full-time employees with Form 1095-C. Other providers of minimum essential coverage must furnish Form 1095-B to responsible individuals. These forms verify that health coverage standards were met for the tax year.

March 16: The Deadline for Flow-Through Entities

This is arguably the most significant date in March for our clients. Timely filing of entity returns ensures that shareholders and partners receive the information they need to manage their personal tax liabilities.

Partnerships (Form 1065)

Calendar year partnerships must file Form 1065 or request an automatic 6-month extension via Form 7004. Crucially, you must provide each partner with their Schedule K-1 (and Schedule K-3 if applicable). If you extend, the return and K-1s will be due by September 15.

S Corporations (Form 1120-S)

S Corporations must file their 2025 income tax return and pay any tax due. Similar to partnerships, shareholders must be provided with their Schedule K-1 and any applicable Schedule K-3. If an extension is needed, file Form 7004 and pay the estimated tax owed to avoid interest and penalties.

S Corporation Elections (Form 2553)

If you intend for your entity to be taxed as an S Corporation for the 2026 calendar year, you must file Form 2553 by this date. Filing late generally means the election will not take effect until 2027, which can have significant tax implications for your business structure.

Withholding Deposits

For businesses adhering to the monthly deposit rule, tax deposits for non-payroll withholding and social security/Medicare/withheld income tax for February payments are due.

March 31: Electronic Filing Deadlines

As part of the industry’s shift toward digital efficiency, March 31 is the deadline for electronically filing several major forms with the IRS:

• Forms 1099 (excluding 1099-NEC) and 1098.
• Forms W-2G (Gambling Winnings).
• ACA Forms 1094-C, 1095-C, 1094-B, and 1095-B.
• Form 8027 (Tip Income).

Electronic filing not only grants you this later deadline but also reduces the likelihood of processing errors.

Adjustments for Weekends and Disasters

If a statutory due date falls on a weekend or legal holiday, it shifts to the next business day. Additionally, if your business or records are located in a federally declared disaster area, you may be eligible for extensions.

You can verify current disaster declarations and relief details here:

• FEMA: Disaster Declarations
• IRS: Tax Relief in Disaster Situations

Strategic Planning for Your Business

Whether you are managing complex estate assets, a family partnership, or a growing business, staying ahead of these dates is vital for peace of mind. If you require assistance with entity valuation, extensions, or preparing for these deadlines, our team in Burlingame is ready to assist.

Contact Sullivan & Company CPA Inc. today to ensure your compliance strategy supports your broader financial goals.