Most individuals file by April 15. S-Corps and partnerships file a month earlier (March 17). Quarterly estimates are due April 15, June 15, September 15, and January 15. FBAR has an automatic extension to October 15.
Every January, the calendar starts feeling a little tighter. Here's the complete 2026 tax filing calendar — the dates that matter for both individuals and business owners.
Individual taxpayers (Form 1040)
- April 15, 2026 — 2025 individual federal return (Form 1040) due. Missouri MO-1040 also due.
- April 15, 2026 — File Form 4868 if you need an extension to October 15. Extension extends time to file, not time to pay.
- October 15, 2026 — Extended 2025 individual returns due.
Quarterly estimated taxes
If you're self-employed, an S-Corp owner, or have significant investment income, you generally need to pay quarterly:
- April 15, 2026 — Q1 2026 estimate
- June 15, 2026 — Q2 2026 estimate
- September 15, 2026 — Q3 2026 estimate
- January 15, 2027 — Q4 2026 estimate
S-Corporations and partnerships
- March 17, 2026 — 2025 S-Corp (Form 1120-S) and Partnership (Form 1065) returns due. Also the deadline to file Form 7004 for an extension.
- March 17, 2026 — Last day to file Form 2553 to elect S-Corp treatment retroactive to January 1, 2026.
- September 15, 2026 — Extended S-Corp / Partnership returns due.
C-Corporations
- April 15, 2026 — 2025 C-Corp return (Form 1120) due (calendar-year corps).
- October 15, 2026 — Extended C-Corp returns due.
Foreign account reporting (FBAR / Form 8938)
- April 15, 2026 — FBAR (FinCEN 114) technically due — but there's an automatic extension to October 15, 2026. No form needed.
- April 15, 2026 — Form 8938 due with your individual tax return (or extended to October 15 with Form 4868).
Payroll & 1099s (employers and business owners)
- January 31, 2026 — W-2s and 1099-NEC must be issued to recipients and filed with SSA/IRS.
- February 28, 2026 — 1099-MISC paper filing deadline (March 31 if e-filed).
- April 30, 2026 — Q1 2026 Form 941 due (each quarter thereafter).
- January 31, 2026 — 2025 Form 940 (FUTA) due.
Missouri-specific dates
- April 15, 2026 — Missouri MO-1040 due.
- April 15, 2026 — Missouri MO-1120 (corporate) due.
- Monthly / Quarterly — Missouri sales tax filings — due dates depend on filing frequency assigned by the Missouri Department of Revenue.
What if I miss a deadline?
If you owe tax and miss the deadline, the IRS charges a failure-to-file penalty (5% per month, capped at 25%) plus a failure-to-pay penalty (0.5% per month) plus interest. The fastest way to limit damage is to file an extension on time and pay an estimate of what you owe.
If you've missed something, don't panic — but don't ignore it. Reach out and we'll help you respond.
The single best thing you can do for your tax situation is plan before December 31 — not scramble after April 15.
Want a printable PDF version of this calendar? Send us a note and we'll email one to you.