Wisconsin · reference

Wisconsin calendar and forms

Every Wisconsin date that matters for the 2026 return, from the last estimated payment in January 2027 to the extended due date in October and the last day to amend; how the extension really works; the forms and schedules an ordinary filer will meet, in the order they come up; free filing, refunds and how to reach the Department. For anyone who files here.

By Charles Trautman, EA, editor

Need to Know Tax · written from Wisconsin Department of Revenue sources, November 3, 2026; updated November 12, 2026 after the election · not yet reviewed by a Wisconsin practitioner

Wisconsin runs on the federal calendar. Form 1 is due the same day as the federal return, April 15, 2027; the four estimated payments fall on the federal dates; and the Wisconsin Department of Revenue honors any federal extension without a request of its own, so a Form 4868 filed with the IRS extends the Wisconsin return to October 15, 2027 as well. The two things to know are that the extension extends filing and not payment, with interest at 1% a month on anything unpaid after April 15, and that Wisconsin’s estimated-tax trigger is $500, lower than the federal $1,000, so people who skate by federally can owe interest here.

The form side has more pieces. Wisconsin applies its own additions, subtractions, deduction and credits to federal AGI, each on its own schedule, but most filers touch Form 1 and one or two of them, usually Schedule SB for Social Security and retirement income. The longer list below is for people who moved, work across the state line, have capital gains, claim the homestead credit, or need to fix a return already filed.

The 2027 filing season, dated

Wisconsin dates for the 2026 return and 2027 payments
Date	What happens	Form
Friday, January 15, 2027	Fourth and final 2026 estimated payment due. It can be skipped if the 2026 return is filed and the balance paid in full by January 31 (verify the weekend date).	1-ES
Late January 2027; the IRS announces the date in January	The Department begins accepting 2026 returns on the day the IRS opens e-filing. In 2026 that was January 26. WisTax opened a little later, in February 2026; the 2027 date is to come.	Form 1
Monday, February 1, 2027	W-2s and 1099s should be in hand; January 31 is a Sunday.	W-2, 1099
Monday, March 1, 2027	Farmers and fishers who skipped estimated payments must file and pay in full by today to avoid interest. The Department generally does not issue refunds before March 1.	Form 1
Thursday, April 15, 2027	Form 1 and Form 1NPR due, and all 2026 tax due. A federal extension carries over automatically; a payment with Form 1-ES by today stops interest. First 2027 estimated payment due. Schedule H homestead claims for 2026 can be filed from now on their own or with the return.	Form 1, 1NPR, 1-ES, Schedule H
Tuesday, June 15, 2027	Second 2027 estimated payment due.	1-ES
Wednesday, September 15, 2027	Third 2027 estimated payment due.	1-ES
Friday, October 15, 2027	Extended due date for the 2026 return, for anyone with a federal six-month extension.	Form 1, 1NPR
Tuesday, January 18, 2028	Fourth 2027 estimated payment due. January 15 is a Saturday and the 17th is a holiday.	1-ES
Tuesday, April 15, 2031	Last day to amend the 2026 return for a refund: four years from the unextended due date.	Form 1 (amended) with Schedule AR
Property tax runs on its own calendar. Wisconsin bills arrive in December; the Lottery and Gaming Credit and First Dollar Credit are already on the bill. The school property tax credit on Form 1 counts tax paid during 2026, whichever year’s bill it was, and the homestead credit uses the 2026 bill.

How the extension really works

Wisconsin has no extension form of its own. Anyone with a federal extension gets the same extension for the Wisconsin return by attaching a copy of Form 4868, or a statement naming the federal provision, when the return is filed. The Department honors it even if the federal return was filed on time, and someone with no federal extension can still claim the Wisconsin one by attaching a statement that they are using the federal six-month provision. Nothing is filed in April.

What the extension does not do is extend the time to pay. Interest runs at 1% a month on tax not paid by April 15, 2027, extension or not; once a return is actually late, the delinquent rate is 18% a year and penalties can follow. The Department’s instruction is specific: pay the expected balance by April 15 with Form 1-ES, the estimated tax voucher, not Form PV, even if the return will be e-filed. An overpayment comes back when the return is filed. Only extensions tied to a combat zone or a federally declared disaster also stop interest.

Estimated payments

Wisconsin requires estimated payments when the tax expected for the year, after withholding and credits, is $500 or more, and withholding covers less than the safe harbor: 90% of this year’s tax or 100% of last year’s, whichever is smaller. There is no 110% rule for higher incomes. A full-year resident who owed no Wisconsin tax last year is exempt. Payments go in four equal installments on Form 1-ES or online at revenue.wi.gov; a mailed payment is timely if postmarked by the due date and received within five days. Underpayment interest is figured on Schedule U with the return.

The people most often caught are retirees doing Roth conversions, the self-employed, landlords, and anyone with a large capital gain, because none of that income has Wisconsin withholding unless they ask for it. Retirees who claim the 67-and-older retirement subtraction should note that it forfeits every Wisconsin credit for the year, but withholding and estimated payments are not credits and still count in full.

Worked example: a Roth conversion and the $500 line

A single retiree, 68, has a $40,000 pension with $1,200 of Wisconsin withholding, $24,000 of Social Security, and converts $60,000 of a traditional IRA to a Roth in 2026 with no state withholding. Last year’s Wisconsin tax was $1,500. Figures use the 2026 indexed deduction and brackets.

Federal AGI: pension, conversion, 85% of Social Security	$120,400
Less Social Security (all of it) and the $24,000 retirement subtraction	−$44,400
Wisconsin income	$76,000
Standard deduction ($13,960 less 12% of income over $20,119) and exemptions ($700 + $250)	−$8,204
Wisconsin taxable income	$67,796
Tax at 3.50% / 4.40% / 5.30%	$2,990
Withholding	−$1,200
Expected balance due	$1,790

The balance is over $500 and withholding is under both safe harbors, so estimated payments are required. The cheapest fix is four payments of $75, which brings prepayments to $1,500, 100% of last year’s tax; the remaining $1,490 is due April 15, 2027 with no interest. Or, since the conversion happened in one quarter, one payment of $300 by the next installment date does the same. Taking the retirement subtraction costs nothing here if the retiree has no credits to lose; a homeowner would weigh the $300 school property tax credit against the roughly $1,300 the subtraction saves.

The forms, in the order a filer meets them

Wisconsin individual income tax forms and schedules, tax year 2026
Form	What it does	Who needs it
Form 1	The resident return: federal AGI, additions, subtractions, the sliding standard deduction and $700 exemptions, the four rates, then credits and payments. Also the amended return, with the box at the top checked.	Every full-year resident who files
Form 1NPR	The nonresident and part-year resident return. Two columns, federal and Wisconsin, with the standard deduction and brackets prorated by the Wisconsin share of income.	Anyone who moved in or out during 2026, or a nonresident with $2,000 or more of Wisconsin gross income
Schedule I	Adjustments to federal AGI where Wisconsin’s 2022 version of the Internal Revenue Code differs from current federal law: bonus depreciation, the dependent care exclusion over $5,000, and the other items in Tax Bulletin 234 (verify which items go here and which on Schedule AD).	Business owners and landlords with bonus depreciation; parents with employer dependent care benefits over $5,000; anyone else with a 2026 conformity difference
Schedule AD	Additions to income: municipal bond interest from other states and most Wisconsin issues, and the other add-backs.	Anyone with tax-exempt interest or a decoupled federal item
Schedule SB	Subtractions: Social Security, the $24,000 / $48,000 retirement subtraction at 67, exempt military and government pensions, U.S. government interest, after-tax medical insurance premiums, the 529, tuition and adoption subtractions, Guard and Reserve pay.	Nearly every retiree, and anyone with a subtraction
Schedule CS	Edvest and Tomorrow’s Scholar 529 contributions, $5,280 per beneficiary for 2026 ($2,640 married filing separately); the result carries to Schedule SB.	Anyone who contributed to a Wisconsin 529 plan
Schedule WD	Capital gains and losses: the 30% exclusion for long-term gains (60% for farm assets), the $3,000 loss limit and carryovers.	Anyone with a federal Schedule D
Schedule 1	Itemized deduction credit: 5% of medical, mortgage interest, charitable and certain other Schedule A amounts above the Wisconsin standard deduction.	Homeowners with large mortgage interest, big medical years, large givers; it does not require itemizing federally
Schedule 2	Married couple credit: 3% of the lower-earning spouse’s earned income, up to $480.	Joint filers where both spouses work
Schedule WI-2441	Child and dependent care credit, 100% of the federal credit figured on Wisconsin expense caps.	Parents paying for child care
Schedule CR	The nonrefundable credits, including the new stillbirth credit and the employer-provided child care credit; Schedule CF carries unused credits forward.	Anyone with a credit beyond the ones printed on Form 1
Schedule OS	Credit for net income tax paid to another state on income Wisconsin also taxes, generally limited to the Wisconsin tax on that income; the limit does not apply to tax paid to Minnesota, Illinois, Iowa or Michigan. Not for wages from the four reciprocal states; the fix there is a refund from that state.	Residents working in Minnesota or any non-reciprocal state, remote workers, owners of out-of-state rentals and partnerships
Schedule PS	Private school tuition subtraction, $4,000 per K-8 pupil and $10,000 per pupil in grades 9–12.	Parents paying private school tuition
Schedule H and H-EZ	Homestead credit, the refundable property tax and rent credit for household income under $24,680 (2025 figure). Can be filed alone. H-EZ is for simple cases: wage, interest, pension and Social Security income, home on one acre or less, no sale or marital change in the year.	Lower-income homeowners and renters who are 62 or older, disabled, or have earned income
Schedule AR	Explanation of changes on an amended return; attaches to Form 1 with the amended box checked. Do not send a copy of the original return.	Anyone amending
Schedule U	Underpayment interest on estimated tax.	Anyone who owed $500 or more and fell short of the safe harbor
Form 1-ES	Estimated tax vouchers and worksheet, and the voucher to use for an extension payment by April 15. Payments can also be made online without the voucher.	Anyone expecting to owe $500 or more after withholding; anyone paying with an extension
Form WT-4	Employee’s Wisconsin withholding exemption certificate, the state counterpart of the federal W-4. Form WT-4A sets a different, usually higher, amount.	Every Wisconsin employee; two-earner couples especially, since the sliding standard deduction pushes the real rate above the schedule
Form W-220	Nonresident reciprocity declaration. Given to a Wisconsin employer by a resident of Illinois, Indiana, Kentucky or Michigan so no Wisconsin tax is withheld from wages.	Reciprocal-state commuters; not filed with the return
All current-year forms and instructions are on the Department’s individual income tax forms page; the 2026 forms replace the 2025 set there in December or January. Paper returns with a payment go to PO Box 268, Madison WI 53790-0001; refund or no-payment returns to PO Box 59, Madison WI 53785-0001; returns claiming the homestead credit to PO Box 34, Madison WI 53786-0001 (verify against the 2026 instructions).

Filing free, checking a refund, reaching the Department

WisTax is the Department’s own free e-file system at revenue.wi.gov, open to full-year residents with a valid Wisconsin driver’s license or ID. It handles Form 1, Schedule H and amended returns, is built for taxpayers rather than preparers, and files only the Wisconsin return. IRS Direct File, which included Wisconsin for 2024 returns, was discontinued by the IRS in November 2025 and will not be offered for the 2027 season. VITA and AARP Tax-Aide sites prepare both returns free for people who qualify.

Refunds. E-filed returns are processed about seven days faster on average than paper, and refunds can be direct-deposited, though the Department does not require it. It generally issues no refunds before March 1, may send a letter asking the filer to verify identity before releasing the money, and asks filers to wait twelve weeks before calling. Where’s My Refund at revenue.wi.gov shows what the call center knows and needs the Social Security number and the refund amount.

Contact. Individual income tax customer service is (608) 266-2486; the main line is (608) 266-6466. The Madison office is at 2135 Rimrock Road, also the address for private delivery services. My Tax Account, the online account system, shows payments posted, letters sent and balances due, and is the quickest way to answer “did my estimated payment post?”

Behind the scenes: why there is no Wisconsin extension form

Wisconsin builds its return on the federal one, so it has always borrowed the federal extension rather than running its own: any extension the IRS grants, for any reason, extends the Wisconsin return by the same period, as long as the filer says so when the return arrives. That is simpler than a separate form, but it invites the mistake the Department sees every spring, treating the extension as permission to pay in October. The advice to pay with Form 1-ES rather than Form PV is plumbing: an April payment coded as an estimated payment posts to the account and is waiting when the return arrives, while a Form PV payment is meant to accompany a return that does not yet exist. The $500 estimated-tax threshold, half the federal figure, is the other reason Wisconsin catches people the IRS does not.

What to bring

Every W-2 and 1099 with Wisconsin withholding in box 17 or the state box
The 2026 estimated payments made, with dates and amounts; My Tax Account can list them
Last year’s Form 1, for the 100% safe harbor and any credit carryovers
A copy of the federal extension, if one was filed
The 2026 property tax bill and proof of payment, or rent paid and whether heat was included, for the school property tax credit or Schedule H
Edvest or Tomorrow’s Scholar statements for Schedule CS
Any letter from the Department, especially an identity verification letter, which holds the refund until answered
If you moved or worked across the state line: dates, and income by period and by state

Questions people ask

Do I have to file anything to get a Wisconsin extension?

No. File the federal Form 4868, or nothing at all if you qualify for a federal extension another way, and attach a copy or a statement to the Wisconsin return when you file it. The extension runs to October 15, 2027. Pay what you expect to owe by April 15 with Form 1-ES to avoid 1% a month interest.

I owe about $800 after withholding. Do I have to make estimated payments?

Yes, if your withholding is also less than 100% of last year’s Wisconsin tax and less than 90% of this year’s. The Wisconsin threshold is $500, not the federal $1,000. The simplest fix is to raise withholding on Form WT-4A so the balance drops under $500, or to pay the difference in four installments.

Can I file the homestead credit without a tax return?

Yes. Schedule H or H-EZ can be filed on its own, and WisTax accepts it. If you also have to file Form 1, attach the schedule to it; mail paper homestead claims to PO Box 34 in Madison.

How do I amend a Wisconsin return?

File Form 1 for the year being changed with the amended box checked at the top, attach Schedule AR explaining each change, and do not include a copy of the original return. You have four years from the original due date for a refund. If the IRS or another state changed your return, file the Wisconsin amendment within 180 days.

How long does a Wisconsin refund take?

The Department asks for twelve weeks before you call, issues almost nothing before March 1, and holds some refunds for an identity verification letter. E-filing with direct deposit is fastest.

I live in Illinois and work in Wisconsin. Do I file here?

Not for wages. Give your employer Form W-220 and Wisconsin withholding stops; you pay Illinois only. If Wisconsin tax was withheld anyway, file Form 1NPR to get it back. Wisconsin income that is not wages, such as a rental or gambling winnings, is still taxed here and still needs a 1NPR. See Moving to Wisconsin.

Federal dates, a borrowed extension, and a $500 trigger

Put the four estimated dates on the calendar, pay by April 15 even if the return comes in October, and remember that Wisconsin asks for estimated payments at half the federal threshold.

Written by Charles Trautman, EA, editor  ·  Need to Know Tax, Lone Tree, Colorado
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Forms and official pages named in this article

Sources and where to check

Updated November 12, 2026, after the November 3 election · tax year 2026 figures · awaiting review by a Wisconsin practitioner