03/15/2026
For many businesses, March 16, 2026 (since March 15 falls on a Sunday) is an important federal tax deadline. The main reason is that calendar-year pass-through entities must file earlier than individuals and C corporations so owners can receive their tax information in time to file their personal returns.
Key Business Tax Deadlines – March 16, 2026
1. Partnerships
• Form 1065 – U.S. Return of Partnership Income
• Applies to partnerships and most multi-member LLCs taxed as partnerships
• Schedule K-1s must be provided to partners by this date
2. S Corporations
• Form 1120-S – U.S. Income Tax Return for an S Corporation
• Schedule K-1s issued to shareholders
These returns are due the 15th day of the 3rd month after the end of the tax year (for calendar-year entities, that’s March 15; when it falls on a weekend, it moves to the next business day).
If the Return Isn’t Ready
Entities can file Form 7004 to request an extension:
• Partnerships & S Corps → automatic 6-month extension to September 15, 2026
Important note:
• The extension is for filing, not for paying any tax that may be due.
Why the Earlier Deadline Exists
Congress moved partnership and S-corp deadlines earlier in 2015 (PATH Act) so that:
• Owners receive K-1s earlier, and
• Individuals can complete their Form 1040 filings by April without waiting on pass-through information.
✅ In short: March 15 (or the next business day) is primarily about 1065 and 1120-S filings and issuing K-1s.