COOK COUNTY PROPERTY TAX APPEALS
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2026 DEADLINE TRACKER · VERIFIED OCTOBER 26, 2026
2026 Cook County property tax appeal deadlines
As of October 26, 2026, Cook County Assessor appeals are open in Proviso through October 27; Lake Township through October 29; Palatine through November 4; Orland through November 6; Jefferson through November 12; Schaumburg through November 19; Thornton through November 23; North Chicago through November 24; Niles through December 3; Rich through December 4; and Hanover through December 7. The Board of Review is open for Lyons, Northfield, Stickney, and West Chicago through November 6, with evidence due November 16 for timely complaints.
Deadlines can change. Confirm the date for your property before filing; this tracker is informational and is not legal advice.
QUICK ANSWERS
What are the 2026 Cook County property tax appeal deadlines?
As of October 26, 2026, Cook County Assessor appeals are open in Proviso through October 27; Lake Township through October 29; Palatine through November 4; Orland through November 6; Jefferson through November 12; Schaumburg through November 19; Thornton through November 23; North Chicago through November 24; Niles through December 3; Rich through December 4; and Hanover through December 7. The Board of Review is open for Lyons, Northfield, Stickney, and West Chicago through November 6, with evidence due November 16 for timely complaints.
How do I know which deadline applies to my property?
In Cook County, the controlling window is tied to the property’s township and the office accepting appeals. Confirm the township from the PIN, identify whether the Assessor or Board of Review is open, and use the official source linked below.
What happens if my township’s deadline recently closed?
You generally cannot use an Assessor filing window after it closes. A later Cook County Board of Review window or another remedy may be available, but eligibility and timing depend on the agency and property, so confirm the next official deadline promptly.
Will a successful appeal lower my property tax bill?
An appeal challenges the property’s assessed value, not the bill directly. A lower assessment can reduce the resulting tax bill, but the final amount also depends on tax rates, exemptions, and other factors.
What evidence should I gather before filing?
Residential appeals commonly use comparable sales, comparable assessments, and property-record corrections. Commercial appeals may also require income and expense statements, rent rolls, vacancy evidence, or an appraisal.
2026 DEADLINE STATUS
Find the deadline that applies to your property
Cook County uses separate Assessor and Board of Review calendars. Start with Open now, then review Opening soon, Recently closed, and Dates pending. Every record identifies the appeal body and links to its official source.
Which townships are open for property tax appeals right now?
Fifteen verified Cook County filing windows are open as of October 26: eleven at the Assessor and four at the Board of Review. Proviso closes first on October 27, followed by Lake Township on October 29. The latest Assessor deadline is Hanover on December 7.
COOK COUNTY
OPEN
Proviso Township
Cook County Assessor 2026 reassessment township. The reassessment notice date is September 14 and the Assessor last file date is October 27. This is not a Board of Review deadline.
COOK COUNTY
OPEN
Lake Township (Cook County)
Cook County Lake Township in Chicago, not Lake County. The Assessor calendar lists September 16 as its notice/open date and October 29 as its last file date. This is not a Board of Review deadline.
COOK COUNTY
OPEN
Palatine Township
The Cook County Assessor appeal window opened September 22 and closes November 4, 2026. This is separate from any Board of Review complaint or evidence deadline.
COOK COUNTY
OPEN
Orland Township
The Cook County Assessor appeal window opened September 24 and closes November 6, 2026. This is separate from any Board of Review complaint or evidence deadline.
COOK COUNTY
OPEN
Lyons Township — Board of Review
The 2026 Cook County Board of Review Group 3 complaint window is open October 8 through November 6. The separate evidence-submission deadline for timely complaints is November 16.
COOK COUNTY
OPEN
Northfield Township — Board of Review
The 2026 Cook County Board of Review Group 3 complaint window is open October 8 through November 6. The separate evidence-submission deadline for timely complaints is November 16.
COOK COUNTY
OPEN
Stickney Township — Board of Review
The 2026 Cook County Board of Review Group 3 complaint window is open October 8 through November 6. The separate evidence-submission deadline for timely complaints is November 16.
COOK COUNTY
OPEN
West Chicago Township — Board of Review
The 2026 Cook County Board of Review Group 3 complaint window is open October 8 through November 6. The separate evidence-submission deadline for timely complaints is November 16.
COOK COUNTY
OPEN
Jefferson Township
The Cook County Assessor appeal window opened September 29 and closes November 12, 2026. This is separate from any Board of Review complaint or evidence deadline.
COOK COUNTY
OPEN
Schaumburg Township
The Cook County Assessor appeal window opened October 6 and closes November 19, 2026. This is separate from any Board of Review complaint or evidence deadline.
COOK COUNTY
OPEN
Thornton Township
The Cook County Assessor calendar, last updated October 17, lists an October 8 notice/open date and November 23 last file date. This is not a Board of Review deadline.
COOK COUNTY
OPEN
North Chicago Township
The Cook County Assessor calendar, last updated October 17, lists an October 9 notice/open date and November 24 last file date. This is not a Board of Review deadline.
COOK COUNTY
OPEN
Niles Township
The Cook County Assessor calendar, last updated October 22, lists an October 20 notice/open date and December 3 last file date. This is not a Board of Review deadline.
COOK COUNTY
OPEN
Rich Township
The Cook County Assessor calendar, last updated October 22, lists an October 21 notice/open date and December 4 last file date. This is not a Board of Review deadline.
COOK COUNTY
OPEN
Hanover Township
The Cook County Assessor calendar, last updated October 22, lists an October 22 notice/open date and December 7 last file date. This is not a Board of Review deadline.
Which property tax appeal deadlines are opening soon?
No verified Cook County window is currently in Opening soon. The Board of Review Group 3 and eleven Assessor township windows are already open. Unpublished dates remain in Dates pending until an official source confirms them.
Which Cook County filing windows recently closed?
Wheeling closed at the Assessor on October 22, Worth closed October 15, and Leyden closed October 14. A closed Assessor window does not determine a separate Board of Review window, which must be checked on the Board’s official calendar.
Recently closed
Wheeling Township
The 2026 Cook County Assessor filing window closed October 22. Check the separate Board of Review calendar for a later township window.
Recently closed
Worth Township
The 2026 Cook County Assessor filing window closed October 15, 2026. Check the separate Board of Review calendar for a later township window.
Recently closed
Leyden Township
The 2026 Cook County Assessor filing window closed October 14, 2026. Check the separate Board of Review calendar for a later township window.
Recently closed
Hyde Park Township
The 2026 Cook County Assessor filing window closed October 8, 2026. Check the separate Board of Review calendar for a later township window.
Recently closed
Calumet Township
The 2026 Cook County Assessor filing window closed October 2. Confirm any later Board of Review window on the Board's official calendar.
Recently closed
Palos Township — Board of Review
The 2026 Cook County Board of Review Group 2 complaint window closed September 29. The separate evidence-submission deadline for timely complaints was October 9.
Recently closed
Maine Township — Board of Review
The 2026 Cook County Board of Review Group 2 complaint window closed September 29. The separate evidence-submission deadline for timely complaints was October 9.
Recently closed
Lakeview Township — Board of Review
The 2026 Cook County Board of Review Group 2 complaint window closed September 29. The separate evidence-submission deadline for timely complaints was October 9.
Recently closed
Elk Grove Township — Board of Review
The 2026 Cook County Board of Review Group 2 complaint window closed September 29. The separate evidence-submission deadline for timely complaints was October 9.
Recently closed
Cicero Township — Board of Review
The 2026 Cook County Board of Review Group 2 complaint window closed September 29. The separate evidence-submission deadline for timely complaints was October 9.
Recently closed
Berwyn Township — Board of Review
The 2026 Cook County Board of Review Group 2 complaint window closed September 29. The separate evidence-submission deadline for timely complaints was October 9.
Recently closed
Lemont Township
The 2026 Cook County Assessor filing window closed September 29. Confirm any later Board of Review window on the Board's official calendar.
Recently closed
Bremen Township
The 2026 Cook County Assessor filing window closed September 24. Confirm any later Board of Review window on the Board's official calendar.
Recently closed
Barrington Township
The 2026 Cook County Assessor filing window closed September 23. Confirm any later Board of Review window on the Board's official calendar.
Recently closed
Northfield Township
The 2026 Cook County Assessor filing window closed September 4, 2026. Check the separate Board of Review calendar for a later township window.
Recently closed
Lyons Township
The 2026 Cook County Assessor filing window closed September 3, 2026. Check the separate Board of Review calendar for a later township window.
Recently closed
West Chicago Township
The 2026 Cook County Assessor filing window closed August 21, 2026. Check the separate Board of Review calendar for a later township window.
Recently closed
Stickney Township
The 2026 Cook County Assessor filing window closed August 12, 2026. Check the separate Board of Review calendar for a later township window.
Recently closed
Elk Grove Township
The 2026 Cook County Assessor filing window closed August 4, 2026. Check the separate Board of Review calendar for a later township window.
Recently closed
Cicero Township
The 2026 Cook County Assessor filing window closed July 31, 2026. Check the separate Board of Review calendar for a later township window.
Recently closed
Maine Township
The 2026 Cook County Assessor filing window closed July 21, 2026. Check the separate Board of Review calendar for a later township window.
Recently closed
Palos Township
The 2026 Cook County Assessor filing window closed July 17, 2026. Check the separate Board of Review calendar for a later township window.
Recently closed
Lakeview Township
The 2026 Cook County Assessor filing window closed July 13, 2026. Check the separate Board of Review calendar for a later township window.
Which Cook County townships still have dates pending?
Bloom and South Chicago township dates are pending. The Cook County Assessor has not published their 2026 notice/open dates or filing deadlines, so no date is inferred.
Dates pending
Bloom Township
The Cook County Assessor calendar, last updated October 22, does not publish a 2026 notice/open date or last file date for Bloom Township. No date is inferred.
Dates pending
South Chicago Township
The Cook County Assessor calendar, last updated October 22, does not publish a 2026 notice/open date or last file date for South Chicago Township. No date is inferred.
WHAT TO DO NEXT
A deadline is only the first decision
Before filing, compare the assessed value with recent sales, review the property record for errors, and decide whether comparable properties support an equity argument. Commercial appeals may also require income, expense, rent-roll, appraisal, or vacancy evidence.
Think your property is over-assessed?
Younis Law Group handles residential and commercial property tax appeals throughout Cook County.