Enterprise
Individual & Small Business
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Federal 2026 estimated tax due dates, for comparison: April 15, 2026, June 15, 2026, September 15, 2026, January 15, 2027.
Who must pay Wisconsin estimated tax?
You must pay Wisconsin estimated tax for 2026 if you expect to owe, after subtracting your withholding and credits, at least $500 in tax for 2026 and you expect your withholding to be less than the smallest of (1) 90% of the tax shown on your 2026 income tax return, (2) 100% of the tax shown on your 2025 income tax return, assuming the return covered 12 months, or (3) 90% of the tax shown on your 2026 income tax return, computed by annualizing your taxable income.
How do you avoid a Wisconsin underpayment penalty?
Smallest of 90% of 2026 tax, 100% of 2025 tax (12-month return), or 90% of annualized 2026 tax. No 110% rule for individuals. Not required if a full-year 2025 resident with no 2025 liability. Filing by January 31, 2027 and paying in full can count as the January 15, 2027 payment (conditions apply). Farmers/fishermen: pay by Jan 15, 2027 or file and pay by March 1, 2027.
How much should you pay?
Start with your federal estimate: the free Quarterly Estimated Tax Calculator works out your 2026 federal payments and safe harbor. Wisconsin figures its own tax, so the state amount is separate.