- Assessor site
- https://www.revenue.wi.gov/Pages/Assessors/home.aspx ↗
- Search by
- office contact via the Wisconsin DOR assessor portal / county Real Property Lister; parcel search via county Ascent/ALRS or local assessor
- Reassessment cycle
- LOCAL town/village/city ASSESSORS (DOR-certified) value all real property as of JANUARY 1; no county assessor offices operate. Each county's REAL PROPERTY LISTER (Ch. 70.09) maintains the parcel database + certifies the roll but does not value. The Wisconsin Dept of Revenue assesses ALL MANUFACTURING property + computes each municipality's EQUALIZED VALUE + oversees. DUAL VALUES: ASSESSED VALUE (local assessor's market estimate; ag on use value) vs EQUALIZED VALUE (DOR's full-market estimate for the municipality); their ratio is the LEVEL OF ASSESSMENT. Law requires each municipality's major classes within 10% of market only ONCE EVERY FIVE YEARS.
- Reassessment trigger
- Every January 1 the assessor maintains values; assessment at full value is required at least once every 5 years (sec. 70.05(5)(b)), and 6 consecutive years out of compliance triggers a DOR SUPERVISED ASSESSMENT. DOR publishes equalized values every August 15.
- Personal & intangible property
- Wisconsin REPEALED its tax on most business personal property effective 2024 (2023 Act 12); the tax now falls almost entirely on real property. Manufacturing REAL property remains DOR-assessed; since Act 12, no personal property (manufacturing included) has been assessed from Jan 1, 2024.
- CRE forecasting note
- Two Wisconsin levers — keep them straight: the ANTI-SALES-CHASING rule (an assessor can't jump your assessment to your purchase price without adjusting comparables in the same market area; proving over-assessment means beating the equalized ratio vs comparable assessments, not citing your price) is separate from the 'DARK STORE' doctrine (whether vacant-store comps fit an occupied big box — Lowe's v. Delavan (2023) upheld the city's assessment and rejected vacant/distressed comps for an operating store); plus DOR's central MANUFACTURING assessment (real property only since 2024). Model the LEVEL OF ASSESSMENT (assessed ÷ equalized) to spot a stale roll; levies apportion by equalized value, so a fast-rising equalized value shifts levy share onto that municipality. Business personal property no longer taxed (Act 12, 2024).
- Residential note
- Your tax bill shows two numbers: the ASSESSED VALUE (your local assessor's figure) and the EQUALIZED (fair market) value the state estimates for the whole municipality. Because the law only requires assessments to be within 10% of market once every five years, your assessed value can drift from market between revaluations — so compare it to what similar homes are actually selling for, not just to the prior year. To contest: review at OPEN BOOK in the spring, then file an objection and testify before the BOARD OF REVIEW (you can't skip it). Claim the Lottery and Gaming Credit and School Levy Credit on your bill, and the income-based Homestead Credit (Schedule H) on your state income-tax return.
RATIO CAUTION — Wisconsin shows TWO values that usually differ. ASSESSED VALUE is the local assessor's number (which the law only requires to be within 10% of market once every five years); EQUALIZED VALUE is the Department of Revenue's estimate of true market value for the whole municipality. If your town hasn't revalued recently, assessed value can sit well off market — the ratio between the two (the LEVEL OF ASSESSMENT) tells you whether your assessment is really high or low, not the raw assessed figure.
REVENUE DRIVEN RATES — The tax rate is a residual: each municipality's share of county, school, technical-college, and state levies is apportioned by its EQUALIZED VALUE, then divided by the local assessed base to set the mill rate. When DOR raises a municipality's equalized value faster than its neighbors', that municipality picks up a bigger slice of every overlying levy even if its own assessed values didn't move — a shift owners don't cause and can't protest parcel-by-parcel.
DISCLOSURE ASYMMETRY — Wisconsin bars an assessor from raising your assessment based solely on a recent arm's-length SALE unless comparable properties in the same market area are adjusted too — the anti-'sales chasing' rule (a uniformity doctrine, distinct from the big-box 'dark store' fight). It cuts both ways: a buyer isn't automatically reassessed to the purchase price, but proving you're over-assessed means showing your assessment is out of line with comparable assessments (via the equalized ratio), not just citing your own recent purchase.
APPEAL DEADLINE — You must work the ladder in order and on time: review at OPEN BOOK, then file a written objection and appear under oath before the local BOARD OF REVIEW — you generally cannot skip it and still appeal. Notices go out at least 15 days before the Board (30 in revaluation years); from there you appeal to circuit court by certiorari or to DOR. Miss the Board of Review window and you forfeit the year.
STATE ASSESSED — Two things are the state's, not the local assessor's: the Department of Revenue assesses ALL MANUFACTURING property in Wisconsin directly (annually, at market), and DOR computes every municipality's EQUALIZED VALUE and can order a SUPERVISED ASSESSMENT if a municipality stays outside 10% of market for six consecutive years.
Note: In Kenosha County, local town, village, and city assessors set values (market value as of January 1) and the Kenosha County Real Property Lister in Kenosha maintains the parcel records and certifies the roll — no Wisconsin county runs its own assessor office. Reach it through the Wisconsin Department of Revenue assessor portal at the link; DOR assesses manufacturing property and computes the municipality's equalized value. Compare your assessed value against the equalized (market) value, review at Open Book in spring, then object before the Board of Review. Claim the Lottery and Gaming and School Levy credits on your bill and the Homestead Credit on your state return.
Primary sources: Wisconsin DOR 2026 Guide for Property Owners + WPAM + Equalized Values pub (assessed market Jan 1, within 10% once every 5 yrs, DOR manufacturing since 1974, equalized value Aug 15 apportions levies, Open Book/Board of Review, roll by first Monday April); sec. 70.05/70.09/70.32/70.75/70.85/70.99/70.995 Wis. Stats.; Janesville/Omro/Platteville assessors + Wisconsin Counties Assn (no county assessor offices, RPL county contact, anti-sales-chasing notice); 2023 Act 12 (PP repeal 2024); WAAO (as of 2026-07-05). Confirm current rules and figures with the assessing authority before any use.