Wisconsin taxes

Wisconsin taxes personal income at 3.5% to 7.65% and does not tax Social Security. A sole proprietor owes nothing at the business level. LLCs, partnerships and corporations file an annual report with the Department of Financial Institutions, from $25. C corporations pay 7.9% franchise or income tax. Corporations and S corporations also pay an economic development surcharge once gross receipts reach $4,000,000, so most small businesses owe none of it.

Personal income tax

Wisconsin residents file Form 1, due April 15, 2026. You can use any federal extension for Wisconsin, even if you file your federal return on time. There is nothing to send in advance: include a copy of your federal extension application, or a statement naming the federal extension you are using, with your Form 1. Interest still runs on any tax not paid by April 15, 2026.

The rate is 3.5% on the first $14,680, 4.4% on the next $35,800, 5.3% on the next $272,810, 7.65% on everything above $323,290 of taxable income. Single and head of household filers use these steps. Married couples filing jointly pay 3.5% on the first $19,580, 4.4% on the next $47,720, 5.3% on the next $363,760, 7.65% on everything above $431,060.

The standard deduction shrinks as income rises, from up to $13,560 single or $25,110 married filing jointly down to nothing at higher incomes. Each person on the return also gets a $700 exemption, plus $250 at age 65 or older. Itemizing works as a credit, not a deduction: 5% of the amount by which medical costs, interest, gifts to charity and casualty losses exceed the standard deduction. State and local taxes do not count.

Return

Form 1

Due date

April 15, 2026. Any federal extension can be used for Wisconsin

Rates

3.5%, 4.4%, 5.3%, 7.65%

Standard deduction

Up to $13,560 single, $17,520 head of household, $25,110 married filing jointly, $11,930 married filing separately, shrinking as income rises

Exemptions

$700 per person, plus $250 at age 65 or older

Social Security

Not taxed

Age 67 and over

Up to $24,000 of retirement income per person can be subtracted, but taking it gives up every credit on the return

Itemized deductions

A credit of 5% of certain items above the standard deduction, not including state and local taxes

Sole proprietor

A sole proprietor with no LLC owes no fee and files nothing with Wisconsin for the business. The annual report is only for registered entities.

Your business profit is taxed on your own Form 1.

Single-member LLC

Every Wisconsin LLC files an annual report with the Department of Financial Institutions each year, however few members it has. It costs $25 and is owed whatever the business earned. It is due by the end of the calendar quarter containing the anniversary of the date the LLC was organized.

The LLC's profit is taxed on your own Form 1.

Partnership

A Wisconsin partnership files Form 3. The profit passes through to the partners, who report it on their own returns.

It also files the annual report with the Department of Financial Institutions, from $25. That fee is confirmed for an LLC, so a partnership should confirm its own. Partnerships and LLCs do not pay the economic development surcharge.

S corporation

A Wisconsin S corporation, which Wisconsin calls a tax-option corporation, files Form 5S. The profit passes through to the shareholders, who report it on their own returns.

It files the annual report with the Department of Financial Institutions, from $25. Once gross receipts reach $4,000,000, it also pays an economic development surcharge based on its Wisconsin net income, capped at $9,800. A smaller business owes none of it.

C corporation

A C corporation files Form 4 and pays 7.9% of its Wisconsin income. A corporation selling into other states counts only its Wisconsin share, measured by Wisconsin sales over total sales.

Once gross receipts from all activities reach $4,000,000, it also pays an economic development surcharge of 3% of the tax, at least $25 and at most $9,800. It also files the annual report with the Department of Financial Institutions, from $25.

Return

Form 4

Franchise or income tax

7.9% of Wisconsin income

Multi-state profit

Wisconsin sales over total sales

Economic development surcharge

3% of the tax, from $25 to $9,800, once gross receipts reach $4,000,000

Annual report

From $25 a year

Estimate your state tax

Pick your business type and enter this year's numbers to see the state business tax Wisconsin charges. It assumes all your sales are in Wisconsin.

An estimate for planning, not tax advice.

Sources

• Wisconsin Form 1 Instructions (I-111), 2025
• Wisconsin Form 1 (I-010), Schedule AD, Schedule SB and the Schedule SB instructions, 2025
• dfi.wi.gov Annual Report instructions (CORP5i) and filing fee schedule
• dfi.wi.gov Business Entities: annual report due quarter
• revenue.wi.gov 2025 Form 4 Instructions (via the Internet Archive)

Last reviewed August 2026.