2026 Filing Calendar
Cook County Appeal Deadlines
Board of Review appeal windows by township. Miss your window and you wait up to three years for the next reassessment cycle.
2026 Triennial Reassessment
City of Chicago window opens May 1
2026 is Chicago's triennial reassessment year — the biggest appeal opportunity in a 3-year cycle. Over 400,000 residential properties are being reassessed. The Board of Review window opens May 1 and closes May 31.
City of Chicago
North & Northwest Suburbs
South & West Suburbs
How the appeal window works
Each township gets one window per year — typically 30 days, opened after the CCAO mails reassessment notices to that township.
Cook County reassesses on a triennial cycle.Your township is in its reassessment year once every three years — that's when your assessment can change significantly and when appeals are most impactful.
You can still appeal in non-reassessment years— but your assessed value won't change unless you had a recent sale or improvement.
Miss the window and you wait.There is no extension. The next appeal opportunity is the following year's Board of Review session for your township.
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