Federal & Wisconsin Tax Due Dates (2026)
- 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).
