How to appeal your Cook County assessment yourself
You can file both Cook County property tax appeals yourself, online, for nothing — and the county's own records show self-filed residential appeals were decreased 51.9% of the time at the Board of Review across 2023–2025.
The short version: there are two separate appeals, not one. The first is to the Assessor, in a window that opens for your township once a year. The second is to the Board of Review, a different elected body, in its own later window — and you can file it whether or not the Assessor changed anything. Most owners file neither. The argument that works at both is the same one: near-identical homes near you are assessed lower.
Filing it yourself
- Find your township. Cook County assesses, reassesses and opens appeal windows township by township, not by city or ZIP code. Our township pages list all 38 with their latest reassessment change and appeal outcomes.
- Check whether your window is open. Windows are short and they differ by township; the Assessor's assessment calendar and deadlines is the authority, and the Board of Review publishes its own township open and close dates separately.
- Read your own assessment. Note the assessed value, the class, and the characteristics the Assessor has recorded for your home — square footage, bedrooms, bathrooms, age, whether there is a basement or an attic. A characteristic recorded wrongly is the cleanest appeal there is.
- Find comparable properties. This is the whole case. You want homes near yours, of the same class, similar in size, age and construction, assessed lower per square foot. The free check does this comparison for you and shows the headline finding before anything is offered.
- File with the Assessor online, inside your township's window. There is no fee. State plainly which comparables you are relying on and why your home is like them.
- File again with the Board of Review when its window for your township opens. This is a fresh filing, not an appeal against the Assessor's answer, and it is where the higher success rate in our data sits.
- Keep what you filed. If you appeal again next year, the comparables and the characteristics you corrected are the starting point.
How self-filed appeals actually ended
of self-filed Assessor appeals changed the value (199,481 closed residential appeals, 2023–2025)
of self-filed Board of Review appeals were decreased (276,525 residential decisions)
of the reductions the Assessor granted carry one identical boilerplate reason, so the file cannot tell you which argument worked
filing fee at either level
Full method, the split by year and by township, and the honest limits are on the study: Who actually wins a Cook County property tax appeal.
What this guide can't do for you
- It is not legal or tax advice, and CivicDelta does not file appeals on anyone's behalf.
- Past outcomes don't predict yours. The shares above describe hundreds of thousands of other people's appeals, decided on their own facts.
- Deadlines move. We print appeal dates only where a person has verified them against the county's published calendar; where we have not, our township pages say so rather than guess. Always confirm with the office before filing.
- A won appeal is not a smaller bill by the same amount. The bill depends on the equalization factor, local tax rates and your exemptions, none of which an appeal changes.
- Commercial property is different, and appeals beyond the Board of Review — the Illinois Property Tax Appeal Board, or the circuit court — are outside both files and outside this guide.
See the glossary for assessed value, market value, equalization factor and Board of Review.
Every figure on this page, and where it came from
Every number above is recomputed from the loaded records each time this page is built. Last rebuilt 2026-09-28.
| Dataset | Dataset ID | Captured |
|---|---|---|
| Assessor - Appeals | y282-6ig3 | 2026-09-28 |
| Assessor - Assessed Values | uzyt-m557 | 2026-09-28 |
| Board of Review Appeal Decision History | 7pny-nedm | 2026-09-28 |
Cook County open data, loaded in full and reconciled against the publisher's own row count.
Questions people ask
How much does it cost to appeal a Cook County property tax assessment?
Nothing. Filing with the Cook County Assessor and with the Cook County Board of Review is free, and both accept online filings. Agents and attorneys charge a fee, usually a share of the first year's saving; the county does not.
Do I need a lawyer to appeal my Cook County assessment?
No. Residential owners file their own appeals in large numbers — 276,525 self-filed residential Board of Review decisions are in the county's records for 2023–2025 alone — and 51.9% of them were decreased.
Can I appeal to the Board of Review if the Assessor turned me down?
Yes. The Board of Review is a separate body and a separate filing, in its own window, and it does not matter what the Assessor decided. You can also go to the Board without having filed with the Assessor at all.
When can I appeal?
In your township's window, which opens once a year at each level and closes within weeks. Cook County publishes the current dates on its assessment calendar and deadlines page; our township pages show the dates only where a person has verified them.
What actually wins an appeal?
The county's own file will not tell you: 91.9% of the residential reductions we hold carry the identical boilerplate reason. What the surviving distinctions point to is unremarkable — comparable properties assessed lower, and wrong characteristics on your own record.