The short answer
The key 2026 federal dates are January 15 (Q4 2025 estimates), February 2 (W-2s and 1099-NECs), March 16 (partnership and S corp returns, and S corp elections for 2026), April 15 (individual and C corp returns plus Q1 estimates), June 15 and September 15 (estimates and extended business returns), October 15 (extended individual and C corp returns), and January 15, 2027 (Q4 estimates).
Month by month
| Date | What's due |
|---|---|
| Thu, Jan 15, 2026 | Q4 2025 estimated tax payment |
| Mon, Feb 2, 2026 | W-2s to employees and the SSA; 1099-NEC to contractors and the IRS; Form 941 for Q4 2025; Form 940 (Jan 31 falls on a Saturday) |
| Mon, Mar 16, 2026 | Partnership (1065) and S corp (1120-S) returns and K-1s for calendar-year entities, or extensions (Form 7004); Form 2553 to elect S corp status for 2026 |
| Tue, Mar 31, 2026 | Electronic filing of most other 1099s with the IRS |
| Wed, Apr 15, 2026 | Individual returns (1040) and C corp returns (1120), or extensions; Q1 2026 estimated tax; 2025 IRA and HSA contributions; FBAR (automatic extension to Oct 15) |
| Thu, Apr 30, 2026 | Form 941 for Q1 2026 |
| Mon, Jun 15, 2026 | Q2 2026 estimated tax |
| Fri, Jul 31, 2026 | Form 941 for Q2 2026 |
| Tue, Sep 15, 2026 | Q3 2026 estimated tax; extended 1065 and 1120-S returns |
| Thu, Oct 15, 2026 | Extended individual and C corp returns; SEP-IRA contributions for extended filers |
| Mon, Nov 2, 2026 | Form 941 for Q3 2026 (Oct 31 falls on a Saturday) |
| Thu, Dec 31, 2026 | Last day for most year-end tax moves: equipment placed in service, charitable gifts, S corp owner payroll and year-end bonuses |
| Fri, Jan 15, 2027 | Q4 2026 estimated tax payment |
When a deadline falls on a weekend or legal holiday, it moves to the next business day. The IRS also postpones deadlines for taxpayers in federally declared disaster areas, so check irs.gov if you've been affected.
State deadlines
Most states follow the federal dates for individual returns, but business, franchise and sales tax deadlines vary widely. Your firm's compliance calendar should include every state where you have nexus.
General information based on federal law for tax year 2026, not tax advice for your situation. State rules vary.