Cook County property tax appeal deadlines
Cook County does not use one countywide appeal deadline. Each township has its own Assessor window and, later, its own Board of Review window.
Find the property first, then confirm its township deadline.
Enter a Cook County address or property PIN.
Free to check first. No credit card required.
Current 2026 township appeal pages
For currently published open windows, use the township pages for the exact stage, filing dates, evidence context, and official source links.
See current Cook County appeal deadlines by township →The two deadlines are separate
First review opportunity.
Second, independent review opportunity.
Township-specific opening and last-file date.
Separate township window published by the Board; pre-registration may open earlier.
A Board filing does not restore the missed Assessor opportunity.
If the Board township window has closed, the Board says you generally wait until the next eligible year.
Where to verify today's deadline
Use the official County calendars before filing. The Assessor calendar lists reassessment notice dates and Assessor filing deadlines and adds Board dates as they become available. The Board publishes its own current township dates and deadlines.
Why a reassessment notice matters
When a township is reassessed, the notice is the homeowner's trigger to inspect the new valuation and decide whether to appeal. Cook County's 2026 calendar says the south and west suburbs are the scheduled reassessment area this year.
What to do after a Cook County reassessment notice →Do not wait for the Board if the Assessor is open
If you want both opportunities, preserve the Assessor filing first. The Board can accept pre-registration before its formal township window, but that does not substitute for an Assessor appeal.
Check your property while its current assessment data and filing window are actionable.
Deadline information can change. Official Cook County calendars and filing systems control.