METHODHow homes are flagged, and how the list did in 2025
The rule
For every residential parcel of classes 202 to 210, 234, 278 and 295, we take the Assessor's assessed value (certified where certified, mailed otherwise) and building characteristics for the newest tax year the Assessor has published in that township. Comparables are homes in the same assessor neighborhood and class, within 15% on building square feet and 15 years on year built, with the same building type and construction quality. A home needs at least ten comparables. Its implied value is the median assessed value per square foot of all its comparables times its own square feet. A home is flagged when its assessed value is at least 10% and $3,000 above that implied value, and not more than 40% above it.
The 2025 test
We ran the rule on the 2025 roll and joined the result to the Board of Review's published 2025 decisions (Cook County Open Data, table 7pny-nedm), counting an appeal as won when the Board lowered the assessed value.
| Attorney-filed appeals | Appeals | Won | Average cut per appeal |
|---|---|---|---|
| Flagged homes | 9,272 | 71.5% | $6,419 |
| Every other home | 121,970 | 47.8% | $1,921 |
Owners who filed flagged homes themselves won 85.7%. Of the 57,542 homes flagged on the 2025 roll, 44,366 were not appealed at all.
What the test does not show: that the list caused the wins. Flagged homes are the ones whose numbers are furthest from their neighbors, which is why they win. Past results do not promise any future decision by the Assessor or the Board.