Cook County, Illinois · Chicago
Cook County property tax appeal guide
Cook County residential assessments use 10% of market value. The Assessor and Board of Review have separate township appeal windows. Check the current office, assessment year and filing instructions before submitting. Choose the Assessor or Board of Review route and follow that office’s current application and calendar.
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Choose the correct filing office
Check which office is accepting appeals for your township and assessment year. An Assessor deadline is not a Board of Review deadline. Each office has its own application, filing calendar and evidence instructions; an Assessor filing does not file a Board of Review complaint.
For an Assessor uniformity appeal, submitting your own comparable-property list is optional: the Assessor's analysts also review comparable properties. A paid packet is optional. If you submit evidence, verify the office's current rules and submission deadline; Board of Review requirements are separate.
Official Assessor residential appeal instructions · Official Board of Review instructions
Cook runs rolling township-by-township windows. The Assessor lists 2026-09-14 as the notice date for Proviso Township and the Assessor accepts appeals through 2026-10-27. Filing with the Assessor is free, and a separate Board of Review window opens later for the same township.
Source: Cook County Assessor — assessment calendar and deadlines · verified September 14, 2026Cook runs rolling township-by-township windows. The Assessor lists 2026-09-16 as the notice date for Lake Township and the Assessor accepts appeals through 2026-10-29. Filing with the Assessor is free, and a separate Board of Review window opens later for the same township.
Source: Cook County Assessor — assessment calendar and deadlines · verified September 17, 2026Cook runs rolling township-by-township windows. The Assessor lists 2026-09-22 as the notice date for Palatine Township and the Assessor accepts appeals through 2026-11-04. Filing with the Assessor is free, and a separate Board of Review window opens later for the same township.
Source: Cook County Assessor — assessment calendar and deadlines · verified September 23, 2026Cook runs rolling township-by-township windows. The Assessor lists 2026-09-24 as the notice date for Orland Township and the Assessor accepts appeals through 2026-11-06. Filing with the Assessor is free, and a separate Board of Review window opens later for the same township.
Source: Cook County Assessor — assessment calendar and deadlines · verified September 25, 2026Cook runs rolling township-by-township windows. The Assessor lists 2026-09-29 as the notice date for Jefferson Township and the Assessor accepts appeals through 2026-11-12. Filing with the Assessor is free, and a separate Board of Review window opens later for the same township.
Source: Cook County Assessor — assessment calendar and deadlines · verified September 29, 2026Cook runs rolling township-by-township windows. The Assessor lists 2026-10-06 as the notice date for Schaumburg Township and the Assessor accepts appeals through 2026-11-19. Filing with the Assessor is free, and a separate Board of Review window opens later for the same township.
Source: Cook County Assessor — assessment calendar and deadlines · verified October 7, 2026Cook runs rolling township-by-township windows. The Assessor lists 2026-10-08 as the notice date for Thornton Township and the Assessor accepts appeals through 2026-11-23. Filing with the Assessor is free, and a separate Board of Review window opens later for the same township.
Source: Cook County Assessor — assessment calendar and deadlines · verified October 9, 2026Cook runs rolling township-by-township windows. The Assessor lists 2026-10-09 as the notice date for North Chicago Township and the Assessor accepts appeals through 2026-11-24. Filing with the Assessor is free, and a separate Board of Review window opens later for the same township.
Source: Cook County Assessor — assessment calendar and deadlines · verified October 12, 2026Cook runs rolling township-by-township windows. The Assessor lists 2026-10-20 as the notice date for Niles Township and the Assessor accepts appeals through 2026-12-03. Filing with the Assessor is free, and a separate Board of Review window opens later for the same township.
Source: Cook County Assessor — assessment calendar and deadlines · verified October 21, 2026Cook runs rolling township-by-township windows. The Assessor lists 2026-10-21 as the notice date for Rich Township and the Assessor accepts appeals through 2026-12-04. Filing with the Assessor is free, and a separate Board of Review window opens later for the same township.
Source: Cook County Assessor — assessment calendar and deadlines · verified October 24, 2026Cook runs rolling township-by-township windows. The Assessor lists 2026-10-22 as the notice date for Hanover Township and the Assessor accepts appeals through 2026-12-07. Filing with the Assessor is free, and a separate Board of Review window opens later for the same township.
Source: Cook County Assessor — assessment calendar and deadlines · verified October 24, 2026Dates not yet published by the county. Windows are announced through the year; check the official calendar or leave your address and we watch it for you. Leyden and Worth left this list on September 1 when the county posted their dates, so it does move.
Official calendar: Cook County Assessor — Assessment Calendar and DeadlinesNot appealing now? Get a spring 2027 reminder
If your filing window is closed or this check has not established a case, sign up for one email in spring 2027 to check Cook County’s official filing calendars. Windows vary by township and office; spring is not a promised opening date.
By signing up, you request one spring 2027 reminder from AppealMyTax. No purchase, automatic appeal, ongoing monitoring or marketing sequence.
Check the current Assessor calendar · Check the Board of Review calendar
- New Trier township: 4,246 homes flagged, a $69.3M assessed-value gap
- Evanston township: 2,536 homes flagged, a $23.1M assessed-value gap
- Oak Park township: 2,507 homes flagged, a $17.0M assessed-value gap
- Norwood Park township: 1,466 homes flagged, a $6.4M assessed-value gap
- Riverside township: 1,120 homes flagged, a $6.1M assessed-value gap
- Rogers Park township: 1,045 homes flagged, a $5.2M assessed-value gap (condo stock undercounted)
- River Forest township: 673 homes flagged, a $7.9M assessed-value gap
Cook County appeal deadline
Separate township filing windows for the Assessor and Board of Review.
Check which office is accepting appeals for your township and assessment year. An Assessor deadline is not a Board of Review deadline. Each office has its own application, filing calendar and evidence instructions; an Assessor filing does not file a Board of Review complaint.
How to appeal in Cook County
1. Identify the open office and township window
Confirm your township and assessment year on the notice. Check the Assessor calendar and, separately, the Board of Review calendar. Do not use one office's closing date to file with the other.
2. File with the office whose route you choose
During an Assessor window, use the Assessor's residential appeal application. A Board of Review complaint is a separate filing through that office's portal or permitted filing method during its own township window.
3. Follow that office's evidence rules
Identify the issue: inaccurate property characteristics, overvaluation, or lack of uniformity. For Assessor uniformity appeals, a homeowner-supplied comparable list is optional because analysts review comparable properties. If submitting evidence, use relevant records and follow the selected office's instructions.
4. Save confirmation and read the decision
Keep your submission, case number and evidence deadlines. An Assessor decision does not replace a Board of Review filing; check the Board's independent calendar if you wish to use that route.
Cook County property tax FAQ
What is the property tax appeal deadline in Cook County, Illinois?
Separate township filing windows for the Assessor and Board of Review. Check which office is accepting appeals for your township and assessment year. An Assessor deadline is not a Board of Review deadline. Each office has its own application, filing calendar and evidence instructions; an Assessor filing does not file a Board of Review complaint.
What form do I use to appeal in Cook County?
Illinois uses the Assessor residential appeal application or a separate Board of Review complaint, filed with the Cook County Assessor or the separate Cook County Board of Review, for the route you choose. There is no filing fee to appeal.
Do I need to buy comparable-property evidence for an Assessor uniformity appeal?
For an Assessor uniformity appeal, submitting your own comparable-property list is optional: the Assessor's analysts also review comparable properties. A paid packet is optional. If you submit evidence, verify the office's current rules and submission deadline; Board of Review requirements are separate.
Other Illinois counties
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