March 22, 2026
If you own property in Cook County, Illinois, you have a limited window each year to appeal your assessment — and missing it means paying whatever the Assessor says, no questions asked.
The Cook County Assessor reassesses properties on a rotating schedule by township. Once your township's appeal window closes, it's closed. No exceptions. No extensions.
The good news: if you're in a South District township, 2026 is your reassessment year — meaning your assessed value is being recalculated right now, and your appeal window is coming up.
These townships are currently in the 2026 reassessment cycle:
Additional South District townships will open throughout spring and summer 2026.
There are two levels of appeal in Cook County:
1. Cook County Assessor's Office This is your first opportunity. Once your reassessment notice arrives, you typically have 30 days to file. This is the most important window — appeals at this level tend to result in the largest reductions.
2. Cook County Board of Review If you're not satisfied with the Assessor's decision (or missed the Assessor window), you can appeal to the Board of Review. They have separate deadlines, usually a few months after the Assessor's window closes.
A successful appeal needs to show your assessed value is higher than comparable properties. You'll need:
This is exactly what Overtaxed IL automates — we pull comparable sales, calculate your potential reduction, and walk you through filing.
Cook County homeowners who successfully appeal typically save hundreds to thousands of dollars per year. With commercial property values declining and residential values rising, 2026 is a particularly strong year to appeal.
Check your reassessment notice as soon as it arrives. If you're in a township that's open for appeals right now, visit overtaxed-il.com to run a free assessment check and see if you're paying too much.