How to Fill Out and Submit Wisconsin Form 1-ES: Amounts and Deadlines

Wisconsin Form 1-ES is the voucher you send with each quarterly estimated income tax payment to the Department of Revenue. You fill in your Social Security Number, name and address, tax year, and payment amount, then either mail it with a check to PO Box 3028, Milwaukee, WI 53201-3028, or pay electronically through the state’s online portal. For the 2026 tax year, installments are due April 15, June 15, and September 15 of 2026, plus January 15, 2027.¹

Do You Actually Need to File It

You need to make estimated payments if you expect to owe $500 or more in Wisconsin income tax for 2026 after subtracting withholding and credits.¹ This typically applies to people with self-employment income, rental income, investment gains, or retirement distributions that aren’t subject to employer withholding. Estates and trusts receiving taxable income are covered too.²

You can skip the vouchers entirely if your withholding and credits will cover the smaller of 90 percent of your 2026 tax or 100 percent of your 2025 tax, assuming last year’s return covered a full twelve months.¹ For steady incomes, the 100-percent-of-prior-year benchmark is usually the easier target because the number is already on your filed return.

Two other outs: if you owed zero Wisconsin tax for 2025, were a full-year resident, and that return covered twelve months, no estimated payments are required for 2026. Active-duty military stationed outside the continental United States are exempt from the requirement altogether.²

Figuring the Installment Amount

The number you write on the voucher comes from the twelve-line worksheet in the Form 1-ES instructions. Start with your 2025 Wisconsin return and project each line forward, adjusting for any income or deductions you know will change.³

The short version: estimate your 2026 Wisconsin income, subtract the standard deduction and exemptions for your filing status, and apply the rate schedule. Wisconsin has four brackets: 3.50 percent, 4.40 percent, 5.30 percent, and 7.65 percent, with dollar thresholds that depend on how you file. Subtract expected credits and any wage withholding. If the remaining figure is under $500, you don’t need to file the voucher. Otherwise, divide it into four equal installments if you’re starting in April, subtract any 2025 overpayment you carried forward, and the result is what goes on each voucher.³

If your income or deductions shift meaningfully mid-year, redo the worksheet and adjust the remaining vouchers accordingly.

Filling Out the Voucher

The voucher is short. You can generate it through the interactive form on the Department of Revenue’s website, which produces a printable PDF pre-populated with your entries.⁴ You supply:

Social Security Number, entered without hyphens. Filing jointly? Add your spouse’s SSN too.
Your full legal name and current mailing address.
The tax year the payment applies to. For payments made during 2026, that’s 2026.
The installment amount from your worksheet.

Trusts use their Federal Employer Identification Number in the SSN field, and estates use the decedent’s Social Security Number.⁴ Check the tax year box carefully. A payment credited to the wrong year is a mess to unwind later.

Submitting the Voucher and Paying

By Mail

Print the completed voucher and mail it with a check or money order made payable to the Wisconsin Department of Revenue:⁵

Wisconsin Department of Revenue
PO Box 3028
Milwaukee, WI 53201-3028

Write the tax year and the last four digits of your Social Security Number on the memo line. If the check and voucher get separated during processing, that notation lets the Department match them.

Online

Wisconsin offers two electronic options through the Department of Revenue’s website: My Tax Account and Quick Pay.¹ My Tax Account is a registered profile where you can schedule installments, view correspondence, and track your balance. Quick Pay works in a single session without an account. Both pull funds directly from your bank using routing and account numbers, and neither adds a fee for that method.

Credit card, Apple Pay, and PayPal payments run through a third-party processor that charges a $1.00 transaction fee plus 2.25 percent of the payment.⁶ On a $2,000 installment that’s about $46 extra, which is why most quarterly filers use the bank transfer option.

Deadlines for the 2026 Tax Year

The four installment dates are:¹

First installment: April 15, 2026
Second installment: June 15, 2026
Third installment: September 15, 2026
Fourth installment: January 15, 2027

You can pay the full year’s estimated tax with the April voucher or split it evenly across the four dates.¹ If your non-withheld income starts partway through the year, begin with the next upcoming deadline and divide the remaining obligation over the installments left. When a due date falls on a weekend or legal holiday, the deadline shifts to the next business day.

Farmers and fishers get a different schedule. If at least two-thirds of your gross income comes from farming or fishing, you can make a single estimated payment by January 15, or skip estimated payments altogether if you file your Wisconsin return and pay the full balance by March 1 of the following year.²

If You Underpay or Miss a Deadline

Wisconsin charges interest, not a flat penalty, on underpaid installments. Interest runs from each quarterly due date until the payment is made or until April 15 of the following year, whichever comes first, and it accrues separately for each installment period. Even if you settle the full year’s tax by April, missing a quarterly deadline can still generate interest for the periods you were short.

You calculate what you owe on Schedule U (Underpayment of Estimated Tax by Individuals and Fiduciaries), filed with your annual return.⁷ You won’t owe underpayment interest if:

Your total tax minus withholding is under $500.²
You paid at least the smaller of 90 percent of your 2026 tax or 100 percent of your 2025 tax, with a full twelve-month prior return.¹
You had zero Wisconsin tax liability for 2025, were a full-year resident, and that return covered twelve months.²
The Department of Revenue determines that a casualty, disaster, or other unusual circumstance makes charging interest inequitable.²

One exception for fiduciaries: estates and trusts with taxable income of $20,000 or more can’t use the 100-percent-of-prior-year safe harbor and must meet the 90-percent-of-current-year threshold.⁸

When Your Income Is Lopsided

Equal quarterly installments assume income arrives at a steady rate. If yours doesn’t (a seasonal business, a fall consulting project, a one-time capital gain), Wisconsin allows the annualized income installment method, which sizes each voucher to the income you actually earned during that period.⁸

You calculate this through Part IV of Schedule U and enter exception code “08” on the underpayment interest line of your return, or “09” if you also have a net operating loss carryforward or carryback.⁸ It’s more paperwork because you’re effectively recomputing your tax four times a year, but for genuinely uneven income it can reduce or eliminate the underpayment interest that a flat-installment approach would generate.

1
Wisconsin Department of Revenue. Individual Income Tax – Estimated Tax Payments
2
Wisconsin State Legislature. Wisconsin Code 71.09 – Payment of Estimated Taxes
3
Wisconsin Department of Revenue. 2026 Form 1-ES Instructions – Estimated Income Tax for Individuals
4
Wisconsin Department of Revenue. Form 1-ES Wisconsin Estimated Income Tax Interactive Voucher
5
Wisconsin Department of Revenue. Tax Return Mailing Addresses
6
Wisconsin Department of Revenue. Credit Card and Other Payment Options
7
Wisconsin Department of Revenue. Underpayment Interest
8
Wisconsin Department of Revenue. 2025 Wisconsin Schedule U Instructions