How to appeal your property taxes in Cook County, Illinois

Where to file in Cook County

How to appeal in Cook County, step by step

1. Find your township's dates

   Every Cook County township has its own appeal window, and it changes every year. The Assessor mails a notice when your township opens, with the last day to file. Look up your township's dates below or on the Assessor's appeal calendar.

   Assessor's appeal calendar

2. Check your property record

   Look up your home on the Cook County Assessor's Office website and check square footage, bathrooms, condition and features. Mistakes are the easiest wins. Use our record card checklist.

3. Step 1: Appeal to the Cook County Assessor online

   File a free appeal online with the Cook County Assessor's Office while your township is open. Choose the filing type (Residential for houses and buildings with up to six units, or Condo/Coop). You need an email address; you can save a draft and upload attachments, such as comparable sales, photos, an appraisal or the letter below, before you submit by the last file date. The result is sent by mail.

   File an appeal online with the Assessor

4. Gather evidence

   What works in Illinois:

   • Recent sales of at least three similar homes nearby
   • Equity comparables: at least three similar homes in the same neighborhood or subdivision
   • Your own recent purchase price, with the closing statement, if it was an arm's-length sale
   • A signed appraisal by a licensed appraiser
   • Dated photos of your home

   More detail

   • Recent sales of at least three similar homes nearby, laid out on the county or PTAB grid sheet
   • Equity comparables: at least three similar homes in the same neighborhood or subdivision with lower assessments (per-square-foot comparisons alone are not enough)
   • Your own recent purchase price, with the closing statement, if it was an arm's-length sale
   • A signed appraisal by a licensed appraiser - generally the strongest evidence; short opinion letters carry little weight
   • Dated photos of your home (required by the Cook County Board of Review) and of comparables

5. Step 2: Appeal to the Cook County Board of Review

   After the Assessor finishes your township, the Cook County Board of Review opens it for appeals for at least 30 days. Filing is free: online through the Board's appeal portal, in person or at a satellite office, and you can pre-register before your township opens. Hearings are held by phone, and evidence can be submitted up to 5 days before the hearing. Property owned by an LLC or corporation must be appealed by an attorney.

   Board of Review online appeals · Board of Review dates and deadlines

6. Step 3: PTAB or circuit court

   Next step: Illinois Property Tax Appeal Board (PTAB) or circuit court tax objection. PTAB: within 30 days of the postmark date on the Board of Review's written decision. Circuit court (tax objection): only after paying the taxes, by the deadline set in the Property Tax Code. File the PTAB Residential Appeal form (PTAB-1A) online through the PTAB eFiling system or by mail to Springfield (no fax/email). Include the Board of Review decision and evidence for at least three comparables. There is no fee. Hearings are held by administrative law judges, usually in the county seat. You can instead pay the tax and file a tax objection complaint in circuit court, which generally requires a lawyer.

   Property Tax Appeal Board: filing an appeal

2026 Cook County appeal dates by township

Dates copied from the official calendars, checked Oct 24, 2026. They can change: confirm on the Assessor's calendar and on your notice before you file.

Sources: Cook County Assessor's Office - Assessment & Appeal Calendar (page last updated 10/22/26); Board of Review dates for Lyons, Northfield, Stickney and West Chicago: Cook County Board of Review - Dates and Deadlines 2026 Session (PDF).

How much could you save?

Enter the market value on your assessment notice and what you think the home would really sell for. We estimate the yearly saving if the board agrees with you.

Free property tax appeal letter

Fill in your details and download a written appeal statement as a PDF. Most boards also require their own appeal form: file the form and attach this letter and your evidence to it.

RobinClaim is a free information site, not a law firm or appraiser. The letter is a template, not legal advice.

Cook County property tax appeal FAQ