Tax Deadlines & Compliance Calendar
Never Miss a Filing Deadline Again
Federal and Wisconsin tax due dates for 2026, all in one place.
Bookmark this page for quarterly estimates, extension deadlines, and everything in between — updated each year.
15+ Years Experience • 375+ Clients Served
Wisconsin disaster relief — deadline postponed to November 2, 2026
If your county is covered by the federal disaster declaration, your federal filing and payment deadline is postponed to November 2, 2026, and Wisconsin follows the federal postponement interest-free. The October 15 extension date below still applies everywhere else. Check whether your county qualifies →
IRS‑verified federal deadlines and Wisconsin Department of Revenue state deadlines for the 2026 filing season (tax year 2025) and 2026 estimated payments. Weekend/holiday rule applies.
- Due: April 15, 2026 (calendar‑year filers).
- Extension: Form 4868 to October 15, 2026 (file ≠ pay).
- IRA/HSA for 2025: allowed through April 15, 2026.
- Q1: April 15, 2026
- Q2: June 15, 2026
- Q3: September 15, 2026
- Q4: January 15, 2027
Standard schedule; special rules apply to farmers/fishermen and fiscal‑year filers.
- Due: March 16, 2026 (weekend shift).
- Extension: Form 7004 to September 15, 2026.
- K‑1s: due same date as return.
- Due: March 16, 2026 (weekend shift).
- Extension: Form 7004 to September 15, 2026.
- K‑1s: due same date as return.
- Due: April 15, 2026 (calendar‑year).
- Extension: Form 7004 to October 15, 2026 (file ≠ pay).
- Corporate estimated (calendar‑year): Apr 15, Jun 15, Sep 15, Dec 15.
- Recipients & IRS/SSA: February 2, 2026 (Jan 31 falls Saturday).
- Recipient copies: often February 2, 2026 (some WHFIT trustees: Feb 17).
- Paper to IRS: March 2, 2026; E‑file: March 31, 2026.
If a due date falls on a Saturday, Sunday, or legal holiday, the deadline moves to the next business day.
Wisconsin State Due Dates
- Due: April 15, 2026 (generally mirrors federal).
- Extension: automatic to October 15, 2026 for filing; payment still due April 15.
- Installments: April 15, 2026; June 15, 2026; September 15, 2026; January 15, 2027.
- Required if you expect to owe $500+ after withholding/credits (see Form 1‑ES instructions).
- Monthly filers: last day of the month following the period (weekend/holiday shift).
- Quarterly (calendar year): Apr 30; Jul 31; Oct 31; Jan 31.
- Annual: Jan 31 (or next business day).
- WT‑6 deposits: monthly or semi‑monthly per assignment (see WI business calendar for specific due dates each month).
- WT‑7 annual reconciliation & W‑2/1099 to DOR: Jan 31.
- Due: March 16, 2026 (15th day of 3rd month; weekend shift).
- Extension: automatic Wisconsin‑only extension to October 15, 2026 (7 months) or 30 days after federal extended due date, whichever is later.
- Due: March 16, 2026 (15th day of 3rd month; weekend shift).
- Extension: up to 6 months (generally to September 15, 2026), or to the federal extended date.
- Due: April 15, 2026 (15th day of 4th month after year‑end).
- Extension: automatic 7‑month WI extension (to November 15, 2026 for calendar‑year) or 30 days after the federal extended date, whichever is later.
- Corporate estimated: required if current‑year tax $500+.
If a due date falls on a Saturday, Sunday, or legal holiday, the deadline moves to the next business day (applies to WI returns and deposits).
