Onalaska to mail reassessment notices after full 2025 revaluation showing median residential increases near 27–28%

Accurate Appraisal, the city’s contracted assessor, told the Onalaska Common Council on June 10 that a full 2025 revaluation of every property in the city will produce substantial assessment changes for many owners but does not by itself increase total tax levies.

Brandon Roche, the statutory assessor for Accurate Appraisal, said the firm used 544 valid, arm’s‑length residential sales from 2023 and 2024 and calculated a coefficient of dispersion, or COD, of 12.73 — below the Wisconsin Department of Revenue’s 15 threshold for acceptable assessment equity. Roche said residential assessments on average increase in the range of 27 to 28 percent; commercial properties show larger average increases, about 32 to 35 percent.

The findings matter because Wisconsin is a market‑driven state and a revaluation must keep assessed values close to the state equalized value. “This year’s revaluation reflects significant market changes,” Addie of Accurate Appraisal said during the presentation, and Roche added that the revaluation is intended to maintain fairness across property types and neighborhoods.

Why it matters: assessment changes change how the tax burden is divided among property owners, not the total amount of tax the city collects. Roche said officials and residents often misinterpret reassessments as automatic tax increases. As the presentation’s accompanying video put it, “Assessors don’t set tax rates. Assessors don’t chase tax dollars.” The assessor’s role is to set values so the local budgets can be divided equitably.

Accurate Appraisal outlined the timeline and appeal process the council and public can expect. Initial notices are scheduled to be mailed in July. The firm will post the initial assessment roll and the full sales analysis (the 544 residential sales, broken down by style and neighborhood) to its website so property owners can see the sales used in their area. Phone appointments are set for July 31 (afternoon) and August 1 (morning); in‑person “open book” appointments and walk‑ins are scheduled for August 4–6. The deadline to file for board of review is 48 hours before the initial meeting (set as 10 a.m. Sept. 8 for a board meeting on Sept. 10 at 10 a.m.). Roche said assessors will monitor appointment demand and add staff and times if needed.

Council members pressed for detail on data sources and procedures. Roche said the firm verified exterior property data through an exterior walk‑through where possible, reviewed building permit records, and used sales, listings and returned income/expense reports for commercial properties (the firm typically gets a 10–15 percent return rate on commercial income/expense requests). On multifamily properties, Roche said units of more than three are treated as commercial by the Department of Revenue and have shown higher increases.

The assessors emphasized that notices and posted sales data should help residents understand individual valuation changes. “We are working hard to educate the community before notices hit,” Roche said, and staff and Accurate Appraisal offered to answer follow‑up questions that arise after notices are mailed.

The council did not take formal action on the assessment at the meeting; the presentation provided a public education update and a schedule for appeals and board of review.