Cook County publishes the result of every appeal it decides. So we counted 133,526 house appeals and 217,670 condominium appeals from 2024, split them by township, and worked out where an appeal's actually worth filing.
Now that spread is the part that really matters. A homeowner in the best township is roughly three times more likely to win than one in the worst, on exactly the same paperwork. Nobody publishes this, so people end up filing blind.
| Township | House appeals | Won | Typical cut | Next reassessed |
|---|---|---|---|---|
| North Chicago | 1,541 | 30.2% | 7.8% | 2027 |
| Jefferson | 20,148 | 27.6% | 6.1% | 2027 |
| Hyde Park | 2,950 | 26.4% | 7.7% | 2027 |
| Lake | 9,172 | 25.3% | 7.1% | 2027 |
| South Chicago | 1,502 | 24.4% | 6.7% | 2027 |
| West Chicago | 4,054 | 24.1% | 7.2% | 2027 |
| Cicero | 1,285 | 23.6% | 7.5% | 2029 |
| Lake View | 5,869 | 23.1% | 5.9% | n/a |
| Lyons | 5,409 | 18.9% | 6.7% | 2029 |
| Thornton | 5,782 | 18.9% | 7.2% | 2029 |
| Northfield | 3,852 | 18.8% | 6.2% | 2028 |
| Hanover | 1,890 | 18.6% | 6.2% | 2028 |
| Wheeling | 4,772 | 18.1% | 5.7% | 2028 |
| Rich | 2,774 | 17.8% | 6.9% | 2029 |
| Rogers Park | 1,661 | 17.7% | 6.4% | 2027 |
| Proviso | 4,443 | 17.6% | 6.1% | 2029 |
| Bloom | 2,906 | 17.5% | 6.6% | 2029 |
| Worth | 6,258 | 17.3% | 5.7% | 2029 |
| Orland | 5,222 | 17.2% | 6% | 2029 |
| Evanston | 1,572 | 16.7% | 6.8% | 2028 |
| Riverside | 784 | 16.6% | 8% | 2029 |
| Norwood Park | 952 | 16.4% | 6.9% | 2028 |
| Leyden | 3,685 | 16.2% | 6.7% | 2028 |
| Schaumburg | 3,610 | 15.9% | 5.9% | 2028 |
| Niles | 4,277 | 15.4% | 6.1% | 2028 |
| Stickney | 1,331 | 15.2% | 5.2% | 2029 |
| Palos | 1,739 | 14.8% | 8.3% | 2029 |
| New Trier | 4,051 | 14.3% | 7.6% | 2028 |
| Barrington | 986 | 13.8% | 9.9% | 2028 |
| Oak Park | 2,544 | 13% | 6.2% | 2029 |
| Lemont | 1,597 | 13% | 7.4% | 2029 |
| Berwyn | 1,460 | 12.9% | 8% | 2029 |
| River Forest | 782 | 12.1% | 6.9% | 2029 |
| Maine | 4,023 | 11.1% | 8.2% | 2028 |
| Bremen | 2,280 | 10.2% | 5.9% | 2029 |
| Palatine | 3,983 | 9.2% | 6.2% | 2028 |
| Elk Grove | 2,258 | 9.2% | 6% | 2028 |
| Calumet | 122 | 8.2% | 11.1% | 2029 |
So the argument that decides Illinois residential appeals is uniformity, which basically just means showing that homes genuinely like yours are assessed lower than yours is. Now that's backwards from most states, where you'd argue market value from recent sales. In Washington, comparing your assessment to a neighbor's isn't even allowed as evidence.
And the board takes the best comparables from both sides, works out what each one's assessed per square foot of living area, and asks where you fall in that range. Above it, they grant. Inside or below it, they don't.
There's a fuller write-up of the method and the 351,196 cases behind it in what actually happens to Cook County property tax appeals.
Cook County gives you two separate free appeals at two different offices. The Assessor opens your township's window once a year, and the Board of Review opens its own afterwards in a different building. It takes the same evidence, and its evidence deadline falls ten days after its filing deadline, so you can file first and send the evidence after that. Missing the Assessor isn't missing the year.
And your township page carries today's dates for both.
Every figure above comes from the Cook County Assessor's published appeals dataset for tax year 2024, counting cases where the certified value came in below the mailed value. Houses are classes 202 through 210, 234 and 278. Condominiums are class 299. The reassessment years were derived from the county's own published assessed values and matched against the Assessor's triennial grouping.