Midwest · WI
How to file Wisconsin sales tax
2026 due dates, filing frequencies, form ST-12, and official filing resources.
- State return: ST-12
- Monthly returns due: 20th of the following month (early-monthly class)
- Filing frequencies: Monthly, Quarterly, Annual
When is Wisconsin sales tax due?
Monthly Wisconsin sales tax returns are due the 20th of the following month (early-monthly class). Quarterly returns are due the last day of the month following the period (Apr 30 / Jul 31 / Oct 31 / Jan 31). When a due date lands on a weekend or federal holiday it moves to the next business day; the 2026 calendar on this page already applies that adjustment.
Wisconsin sales tax due dates for 2026
Every date below comes from the state's published deadline rule (dataset 2026.07.0) and is already moved to the next business day when it lands on a weekend or federal holiday. Your account's assigned filing frequency decides which table applies.
Monthly Wisconsin sales tax due dates
Rule: 20th of the following month (early-monthly class). This cadence is flagged for manual review against the state source before relying on it.
| Period | Period ends | Return due |
|---|---|---|
| January 2026 | Jan 31, 2026 | Feb 20, 2026 |
| February 2026 | Feb 28, 2026 | Mar 20, 2026 |
| March 2026 | Mar 31, 2026 | Apr 20, 2026 |
| April 2026 | Apr 30, 2026 | May 20, 2026 |
| May 2026 | May 31, 2026 | Jun 22, 2026 (moved: 2026-06-20 falls on a Saturday) |
| June 2026 | Jun 30, 2026 | Jul 20, 2026 |
| July 2026 | Jul 31, 2026 | Aug 20, 2026 |
| August 2026 | Aug 31, 2026 | Sep 21, 2026 (moved: 2026-09-20 falls on a Sunday) |
| September 2026 | Sep 30, 2026 | Oct 20, 2026 |
| October 2026 | Oct 31, 2026 | Nov 20, 2026 |
| November 2026 | Nov 30, 2026 | Dec 21, 2026 (moved: 2026-12-20 falls on a Sunday) |
| December 2026 | Dec 31, 2026 | Jan 20, 2027 |
- Wisconsin has two monthly classes: early monthly (> $3,600/quarter) due the 20th; regular monthly due the last day of the following month. The earlier date is shown — verify the assigned class.
Quarterly Wisconsin sales tax due dates
Rule: Last day of the month following the period (Apr 30 / Jul 31 / Oct 31 / Jan 31).
| Period | Period ends | Return due |
|---|---|---|
| Q1 2026 | Mar 31, 2026 | Apr 30, 2026 |
| Q2 2026 | Jun 30, 2026 | Jul 31, 2026 |
| Q3 2026 | Sep 30, 2026 | Nov 2, 2026 (moved: 2026-10-31 falls on a Saturday) |
| Q4 2026 | Dec 31, 2026 | Feb 1, 2027 (moved: 2027-01-31 falls on a Sunday) |
Annual Wisconsin sales tax due dates
Rule: January 31 following the calendar year (last day of month following the period).
| Period | Period ends | Return due |
|---|---|---|
| Calendar year 2026 | Dec 31, 2026 | Feb 1, 2027 (moved: 2027-01-31 falls on a Sunday) |
Wisconsin filing notes
- Returns and ACH-debit payments via My Tax Account must be received by 4:00 p.m. Central on the due date.
Return and form
The principal repository-tracked return is ST-12. Paper eligibility is taxpayer-specific; electronic filing or a waiver may control.
Tracked form version: S-012 (R. 4-25) — April 2025
Paper filing posture: taxpayer specific
Official Wisconsin filing resources
File Wisconsin sales tax from reviewed data, not spreadsheets
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Workflow support does not by itself establish registration, filing authority, credentials, agency acceptance, or tax advice. Confirm your assigned filing frequency with the state.
Wisconsin sales tax filing questions
When is Wisconsin sales tax due?
Monthly Wisconsin sales tax returns are due the 20th of the following month (early-monthly class). Quarterly returns are due the last day of the month following the period (Apr 30 / Jul 31 / Oct 31 / Jan 31). When a due date lands on a weekend or federal holiday it moves to the next business day; the 2026 calendar on this page already applies that adjustment.
How often do you file sales tax in Wisconsin?
Wisconsin assigns a filing frequency to each account. The published cadences are monthly, quarterly and annual filing; the state assigns the frequency based on tax volume and notifies the account, so confirm the assigned basis before relying on a calendar.
What form is used to file Wisconsin sales tax?
The Wisconsin return tracked here is ST-12. The principal repository-tracked return is ST-12. Paper eligibility is taxpayer-specific; electronic filing or a waiver may control.
What happens if a Wisconsin due date falls on a weekend or holiday?
The due date moves to the next business day. In 2026, 6 of the Wisconsin due dates listed on this page are adjusted for a weekend or federal holiday; each adjusted date is marked in the calendar.
Can Wisconsin sales tax be filed on paper?
Paper filing posture tracked for Wisconsin: taxpayer specific. The principal repository-tracked return is ST-12. Paper eligibility is taxpayer-specific; electronic filing or a waiver may control.