Cook County's 2026 reassessment by township: Worth up a median 22%, Proviso 19%
Computed from the Cook County Assessor's open Assessed Values data (refreshed Sept. 15, 2026) · First-pass values before appeals · Journalists: cite freely with a link.
| Township | Notices mailed | Assessor appeals close | Median parcel change | Up >10% | Up >20% | Down | Parcels compared | |
|---|---|---|---|---|---|---|---|---|
| Worth | Sept. 1 | Oct. 15 | +22.2% | 88% | 57% | 2% | 56,709 | |
| Proviso | Sept. 14 | Oct. 27 | +19.0% | 76% | 46% | 8% | 47,207 | |
| Orland | Sept. 24 | Nov. 6 | Not in the county's open data yet (file last refreshed Sept. 15). Will be added after the next refresh. | |||||
In Worth Township, the median residential parcel's assessed value went from $20,556 to $25,000, roughly $206,000 to $250,000 in estimated market value at the 10% residential level. Combined assessed value is up +22.3%, and 88% of parcels rose more than 10%.
In Proviso Township, the median went from $23,000 to $28,000, roughly $230,000 to $280,000 in estimated market value. Combined assessed value is up +19.9%, and 76% of parcels rose more than 10%.
What homeowners can do
Cook County appeals run in two stages: first the Assessor, per township, then the Board of Review. Dates for every township are on the Assessor's calendar. A township-wide jump does not mean your own value is wrong; the question is whether your new value is higher than comparable homes nearby. Our free checker looks that up for any address in about two minutes with sources shown, and the Cook County appeal guide covers the process. We are a research tool, not a law or tax firm, and you file any appeal yourself.
The township numbers are averages. Enter your address and we'll compare your new value against nearby comparable homes, sources shown, in about two minutes.
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Methodology
Source: Cook County Assessor, Assessed Values (refreshed Sept. 15, 2026). We compared each parcel's 2026 first-pass (mailed) value with its 2025 Board of Review final value, residential classes 200-299 (including condos), same PIN and same class. New, retired and reclassified PINs are excluded. Because residential property is assessed at 10% of market value (Assessor glossary), a percent change in assessed value equals the change in estimated market value. 2026 values are before any appeals. Deadlines come from the Assessor's calendar (updated Sept. 29, 2026) and can change; confirm on your notice. Questions or the query: hello@grovehopper.com.