Cook County Property Tax Appeal 2026
How to appeal your property assessment in Cook County (Chicago), IL. Everything below is pulled from Cook County Assessor’s Office. Always confirm the current details with the county before filing — this is general information, not legal advice.
Appeals open on a rolling, township-by-township schedule. Each township has roughly a 30-day filing window when its reassessment notice is issued.
$285,000
~2.1% effective rate
Residential Appeal (filed online with the Assessor or Board of Review)
Cook County property tax appeal deadline 2026
The 2026 deadline to appeal your Cook County property assessment is Appeals open on a rolling, township-by-township schedule. Each township has roughly a 30-day filing window when its reassessment notice is issued.. File your Residential Appeal (filed online with the Assessor or Board of Review) with Cook County Assessor’s Office on or before that date — miss it and you generally wait until next year. File as early in the window as possible to secure a hearing slot.
Who assesses & hears your appeal
Cook County Assessor’s Office
Appeals are heard by the Cook County Assessor (first level) and Cook County Board of Review (second level).
How to file in Cook County
Online via the Cook County Assessor portal
www.cookcountyassessor.comSecond-level appeal via the Cook County Board of Review
www.cookcountyboardofreview.comCook County reassesses on a triennial cycle and opens appeals township by township, so your window depends on where your property sits. You can appeal to the Assessor first and, separately, to the Board of Review.
Cook County property tax appeal FAQ
When can I appeal my Cook County assessment?
Cook County opens appeals on a rolling township schedule. When your township’s reassessment notice is mailed, you generally have about 30 days to file. Check the Assessor’s calendar for your township’s open dates.
Can I appeal to both the Assessor and the Board of Review?
Yes. Cook County has two independent levels: you can file with the Assessor’s Office first, and separately file with the Board of Review, which has its own filing window.
Deadlines, forms, and contact details change — always confirm with Cook County Assessor’s Office before filing. This is general information, not legal advice.
Appeal your Cook County assessment
Check your property for $4.99 (credited), then get the full comparable-sales packet and AI appeal letter for a flat $29 — $19 at launch. Built for IL filings.