The 2026 Small Business Tax Calendar: Deadlines You Can’t Miss

If you run a small business, your calendar is one of your most powerful tax-planning tools. Missing a single IRS deadline can trigger penalties, interest, and hours of avoidable cleanup work.​

2026 also comes with a calendar quirk that can quietly trip up busy owners. January 31 falls on a Saturday, which pushes several familiar filing dates into the following week. You technically get more time, but the IRS will not excuse tech issues, mailing delays, or last‑minute chaos on your side.​

This guide walks you through the key 2026 tax deadlines for small businesses, S‑corps, and partnerships so you can plan ahead, protect your cash flow, and avoid costly surprises.

Quick-glance Q1 2026 tax dates

• January 15, 2026 – 4th quarter 2025 estimated tax payment due.​
• February 2, 2026 – Deadline to provide W‑2s to employees and 1099‑NECs to contractors (pushed from January 31).​
• March 16, 2026 – S‑Corp (Form 1120‑S) and Partnership (Form 1065) tax returns due (pushed from March 15).​

Pin these dates in your calendar now, then read on for who they apply to and how to prepare.

January 15, 2026: Final 2025 estimated payment

January 15 is the due date for your 4th quarter 2025 estimated tax payment. This applies to many sole proprietors, single‑member LLCs, and owners whose withholdings don’t fully cover their tax liability.​

If you consistently owe more than you expect in April, tightening up your estimated payments helps smooth cash flow and minimizes underpayment penalties. Before you send this payment, make sure your 2025 books are as up to date as possible so your estimate is based on real numbers, not guesswork.

February 2, 2026: W‑2 and 1099‑NEC deadline

Because January 31 lands on a Saturday in 2026, the usual W‑2 and 1099 deadline moves to Monday, February 2. By this date, you must:​

• Provide W‑2s to employees.
• Provide 1099‑NECs to qualifying contractors.

Use the “extra” weekend to clean up your records rather than to procrastinate. Review your contractor list, confirm addresses, and double‑check that each worker is correctly classified as an employee or contractor. Misclassification can be far more expensive than filing a form a day or two early.

March 16, 2026: S‑Corp and partnership returns

In 2026, March 15 falls on a Sunday, so S‑Corp and partnership returns are due Monday, March 16. That means:​

• S‑Corporations must file Form 1120‑S (or extend) by March 16.
• Partnerships and multi‑member LLCs must file Form 1065 (or extend) by March 16.

These entities are pass‑throughs, so getting these returns done on time is critical for issuing Schedule K‑1s to owners. A late return delays your personal filing, increases stress, and may trigger penalties that could have been avoided with better preparation.

How to actually use this 2026 tax calendar

Having the dates is helpful, but turning them into a simple system is where the real value lies. A few practical steps:

• Block deadlines on your calendar 30, 14, and 7 days in advance.
• Coordinate with your bookkeeper or tax pro so they know exactly when they need finalized books.
• Close your books monthly so estimated payments and filings are based on accurate reports, not rough estimates.​

For example, if you are an S‑Corp that pays contractors, aim to finalize your 2025 books by mid‑January so your W‑2s, 1099s, and March 16 corporate filing are all based on clean, reconciled numbers.

Stay compliant without last-minute panic

The 2026 small business tax calendar is straightforward once you see all the moving pieces in one place. By planning around the January 31 weekend shift and the March 16 due date, you can protect your margins and spend more time running the business—not fighting the IRS.

If you want help turning these deadlines into a proactive tax and cash‑flow plan, consider partnering with a fractional CFO or tax strategist who can keep your books clean, your filings on time, and your tax surprises to a minimum.