Cook County Property Tax Appeals 2026: Deadlines, Evidence & How to File

Property taxes feel high when assessments are high. You can’t appeal your tax bill directly—but you can appeal the assessed value that drives it.
In Cook County, homeowners get two chances to appeal each year—first with the Assessor’s Office (CCAO), then with the Board of Review (BOR).
This guide covers both appeal steps, 2026 township deadlines, evidence that actually works, and what to do if you miss a window.

Quick answer

• Where do I file? Start with the Cook County Assessor (CCAO) when your township opens. You can also file directly with the Board of Review (BOR) when its window opens.
• What’s my deadline? Appeal windows are by township and typically ~30 days. Check the Assessor’s deadlines and BoR deadlines.
• Not happy with BOR’s decision? You can appeal to the Illinois Property Tax Appeal Board (PTAB) within 30 days of the BOR decision.

Who assesses your property and when

Cook County reassesses properties on a three-year cycle across three regions: North/Northwest suburbs, South/Southwest suburbs, and the City of Chicago.
In 2026, the South & West Suburban Cook County townships are being reassessed.

Even if your township isn’t being reassessed this year, you can still appeal when its appeal window opens.

2026 deadlines: how to find your exact last day to file

Appeal windows open and close by township. Your assessment notice shows the last file date, and both the Assessor and BOR publish calendars.

Typical timing is about 30 days from the open date.
If you miss the Assessor window, you can still appeal later at the BOR. Both calendars are here:

• CCAO: Assessment & Appeal Calendar
• BOR: Dates & Deadlines + BOR Appeals Portal

Two appeal tracks (pick one or run both)

1. CCAO → BOR → PTAB

   • File first with the CCAO. If the result is unsatisfactory, file again at the BOR when that window opens.
   • If still unsatisfied, file at PTAB within 30 days of the BOR written decision.

2. Direct to BOR

   • You may skip the Assessor and file directly with the BOR for that tax year’s window.
   • If the BOR result is weak, you can still appeal to PTAB.

What evidence actually helps

Bring facts, not feelings.

• 3 to 5 recent sales comps for similar homes (size, style, location, condition)
• Unequal assessment (equity) comps showing your assessed value per square foot is higher than similar nearby properties
• Property record errors (bed/bath count, finished area, condition, or class) with proof such as photos, permits, or appraisals

A Certificate of Error may correct certain qualifying errors in prior-year assessments or exemptions. It is not a general substitute for a missed valuation appeal. Check eligibility with the Assessor rather than assuming any late disagreement qualifies.

Step-by-step: filing your appeal

1. Check your township window (Assessor and BOR). Mark the last file date.
2. Pull evidence (sales + equity comps, and fix any property-record errors).
3. File online with the CCAO during its window—or pre-file with BOR when it opens.
4. Monitor decisions:
   • If CCAO result is weak, file at BOR.
   • If BOR result is weak, file at PTAB within 30 days.
5. Confirm your savings: ensure the reduction reflects on your next tax bill.

FAQs

How long do I have to appeal?

About 30 days from your reassessment notice (CCAO); BOR windows are separate by township. Always verify the last file date on both official calendars.

Can I appeal my Cook County property taxes every year?

Yes. Even if your township isn’t being reassessed, you can still appeal each year when your township window opens. Annual appeals help correct data errors and keep your assessment fair.

What happens after I file my appeal?

The Assessor or Board of Review reviews your evidence and issues a written decision. If your reduction isn’t reflected on your next tax bill, follow up or appeal to PTAB within 30 days.

Can I skip the Assessor and go straight to the Board of Review?

Yes, direct to BOR is allowed. Some owners file both (Assessor and then BOR) to maximize chances.

What if I miss both the Assessor and BOR windows?

If there’s a factual error in a prior year or a missed exemption, ask about a Certificate of Error to correct it retroactively.

What is PTAB and what’s the deadline?

PTAB is a statewide appeal body. You generally have 30 days from the BOR decision notice to file. Read PTAB’s filing instructions here.