The 2026 S-Corp and LLC Tax Deadline Calendar

Last Updated: April 2026 | Source-Backed Research

Maintaining compliance is the most important responsibility of an S-Corp owner. Missing a federal filing deadline can trigger automatic penalties that quickly erase any tax savings you’ve achieved through the structure. This calendar covers the critical dates for the 2026 tax year, including corporate filings, payroll reports, and individual estimated payments.

Important Disclaimer: This calendar is for educational purposes only. While we verify these dates against official IRS publications, you should always confirm deadlines with your CPA or a qualified tax professional. Some states may have different filing dates or unique franchise tax requirements.

Q1: 2026 Corporate Filings and Elections

The first quarter of 2026 is when you wrap up the 2025 tax year and set your structure for the new year.

  • January 15, 2026: Final 2025 quarterly estimated tax payment (Form 1040-ES) due.
  • January 31, 2026: Deadline to send Form W-2 to employees and file with the SSA. Also the deadline for Form 1099-NEC for contractors.
  • March 16, 2026: The S-Corp Deadline. Form 1120-S is due for calendar-year S-Corporations (since March 15 falls on a Sunday). This is also the deadline to file for a 6-month extension (Form 7004).
  • March 16, 2026: Deadline to file Form 2553 to elect S-Corp status effective for the 2026 tax year.

Q2: Individual Returns and 2026 Estimates

  • April 15, 2026: Individual Income Tax Return (Form 1040) due.
  • April 15, 2026: Q1 2026 Estimated Tax Payment due.
  • April 30, 2026: Q1 Payroll Tax Return (Form 941) due.
  • June 15, 2026: Q2 2026 Estimated Tax Payment due.

Q3: Extensions and Fall Compliance

  • July 31, 2026: Q2 Payroll Tax Return (Form 941) due.
  • September 15, 2026: Final deadline for extended S-Corp returns (Form 1120-S).
  • September 15, 2026: Q3 2026 Estimated Tax Payment due.

Q4: Year-End and 2027 Planning

  • October 31, 2026: Q3 Payroll Tax Return (Form 941) due.
  • December 31, 2026: Deadline for shareholders to take their final 2026 salary and ensure "Reasonable Compensation" targets are met.
  • January 15, 2027: Q4 2026 Estimated Tax Payment due.

Late Filing Penalties

The IRS assesses automatic penalties for late S-Corp returns. For the 2025/2026 tax years, the penalty for filing a late Form 1120-S is typically **$235 per month, per shareholder**, for up to 12 months. Even if no tax is owed, this penalty is applied for failing to file an informational return on time.

Source: IRS 1120-S Instructions (Late Filing of Return)

Tips for Meeting Deadlines

  1. Automate Your Payroll: Services like Gusto or ADP handle the quarterly Form 941 and annual W-2 filings automatically, reducing the risk of manual errors.
  2. E-File Extensions: If your bookkeeping isn't ready by early March, always file Form 7004. It's a "no-questions-asked" extension that gives you 6 more months to file without the late-filing penalty.
  3. Keep a Tax Calendar: Set reminders for the 15th of March, April, June, September, and January to ensure your estimated payments and corporate filings stay on track.

Official Resources

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