Wisconsin tax deadlines in 2026: filing dates and estimated payments
Deadlines that fall in calendar 2026: the 2025 return and the 2026 estimated payments. Different year? See Wisconsin 2025 →
Wisconsin deadlines in 2026
| 2025 individual return due | April 15, 2026 |
|---|---|
| Extended filing deadline | October 15, 2026 |
| Payment due | April 15, 2026, extension or not |
| Final 2025 estimated payment | January 15, 2026 |
| 2026 estimated payments | April 15, 2026 · June 15, 2026 · September 15, 2026 · January 15, 2027 |
Conforms to the federal deadline; follows the federal extension to October 15.
Wisconsin estimated tax payments in 2026
You must pay Wisconsin estimated tax for 2026 if you expect to owe at least $500 after subtracting withholding and credits, and expect withholding to be less than the smallest of 90% of 2026 tax, 100% of 2025 tax, or 90% of 2026 tax computed on annualized income.
| Q1 (2026 tax year) | April 15, 2026 |
|---|---|
| Q2 (2026 tax year) | June 15, 2026 |
| Q3 (2026 tax year) | September 15, 2026 |
| Q4 (2026 tax year) | January 15, 2027 |
| Voucher | Form 1-ES, Wisconsin Estimated Income Tax Voucher |
| Underpayment safe harbor | If you do not prepay at least 90% of your 2026 tax liability or 100% of your 2025 tax, whichever is smaller, you may be subject to interest on the underpayment; no payments required if the amount owed after withholding is under $500. |
| Pay online | tap.revenue.wi.gov |
Farmers and fishers may pay in full by January 15, 2027 or file and pay by March 1, 2027 with no estimates. The fourth installment is not required if the 2026 return is filed and paid by January 31, 2027.
Source: revenue.wi.gov, read September 3, 2026. “You may pay all your estimated tax at that time or in four equal installments on or before April 15, 2026, June 15, 2026, September 15, 2026, and January 15, 2027.”
All 51 jurisdictions in one table: state estimated tax payment dates for 2026.
Wisconsin extensions
Every state's rule in one table: which states accept the federal extension in 2026.
| Does Wisconsin accept the federal extension? | Yes. A federal extension is honored; no state form. |
|---|---|
| Original due date | April 15, 2026 |
| Extended due date | October 15, 2026 |
| Payment | Still due April 15, 2026. The extension is to file, not to pay. You owe interest on any tax not paid by April 15, 2026 even with an extension to file. |
| How to get it | Attach a copy of federal Form 4868 (or a statement electing the federal extension provision) to the Wisconsin return; no separate state form exists and you can use the federal provision even if you did not need a federal extension. |
Source: revenue.wi.gov, read September 3, 2026. “If you have an extension for filing your federal return, this automatically gives you a 6-month Wisconsin extension, provided you attach a copy of your federal extension application to your Wisconsin income tax return.”
Federal deadlines in 2026
| 2025 Form 1040 | April 15, 2026 · extension October 15, 2026 |
|---|---|
| 2025 S-corp (1120-S) & partnership (1065) | March 16, 2026 |
| 2025 C-corp (Form 1120) | April 15, 2026 |
| 2026 federal estimated payments (1040-ES) | April 15, 2026 · June 15, 2026 · September 15, 2026 · January 15, 2027 |
Source: IRS Publication 509 and Form 1040-ES instructions, irs.gov.
Frequently asked questions
When are Wisconsin state taxes due in 2026?
Your 2025 Wisconsin individual income tax return is due April 15, 2026. If that date falls on a weekend or legal holiday, the deadline moves to the next business day. An extension moves the filing deadline to October 15, 2026, but any tax owed is still due on the original date.
When are Wisconsin estimated tax payments due in 2026?
Wisconsin estimated payments for the 2026 tax year are due April 15, 2026, June 15, 2026, September 15, 2026, January 15, 2027. Use Form 1-ES, Wisconsin Estimated Income Tax Voucher or pay online. The final installment for 2025 was due January 15, 2026.
Does Wisconsin accept the federal extension?
Yes. A federal extension is honored; no state form. The extended filing deadline is October 15, 2026, and tax is still due by April 15, 2026.
Does a Wisconsin extension give me more time to pay?
No. An extension extends the time to file, not to pay. To avoid penalties and interest, pay what you expect to owe by April 15, 2026.
Dates are the statutory deadlines that fall in 2026 and move to the next business day when they land on a weekend or holiday. Each section links to the source it was checked against. Always confirm with the Wisconsin tax agency or the IRS before relying on a date. This is general information, not tax advice.