A property tax attorney represents property owners in challenging the assessed value the county has placed on their property. In Cook County that means filing at the Assessor's office, at the Board of Review, and — where the county's decision is still wrong — at the Illinois Property Tax Appeal Board or in circuit court. The assessment is the one input to your tax bill that can be contested; the tax rate and the state equalization factor are set elsewhere and are not open to challenge.
What the county's own outcomes actually show
These are county-published results for every Cook County appellant — represented or not, ours and everyone else's. They are not this firm's results.
| Venue | Appeals decided | Received a reduction | Avg. cut (of AV, winners) |
|---|---|---|---|
| Board of Review, residential, 2025 | 447,784 | 189,516 (42%) | 6.4% |
| Assessor, residential, 2025 | 335,919 | 49,454 (15%) | 9.2% |
| Commercial (Class 5), 2021–2025 | 402,187 | 145,449 (36%) | 20.3% |
The two venues behave in opposite directions, and that is the single most useful thing to understand before filing. The Assessor grants reductions less often — about one appeal in seven — but the reductions granted are larger. The Board of Review grants them far more often, closer to two in five, but cuts less on average. An appeal strategy that treats the two as interchangeable is leaving something on the table at one venue or the other.
Commercial property is a different exercise again: reductions are granted in roughly a third of decided appeals, and the average successful cut is more than three times the residential figure — because commercial value turns on income and expense evidence rather than on comparable sales.
Do you need an attorney to appeal?
No. An individual homeowner may file a Cook County assessment appeal without counsel, and many do — hundreds of thousands of appeals are filed each year. If your case is a straightforward uniformity argument on a single-family home and you have the time to assemble comparables and meet the deadline, filing yourself is a reasonable choice.
Representation tends to matter when the case stops being simple:
- Income-producing property. Commercial, industrial and multi-unit residential appeals are argued on rent rolls, leases and operating statements. The evidence is different in kind from residential comparables, and the amounts at stake are larger.
- The county said no and you think it was wrong. A denial at the Assessor is not the end. The Board of Review is an independent second review, and beyond it the Property Tax Appeal Board and the courts. Each has its own rules, forms and evidentiary expectations.
- Something in the record is wrong. Square footage, room count, condition, a finished basement that does not exist — factual errors in the county's property record require documentation to correct, and they persist until someone corrects them.
- Ownership is an entity, or the property is held in trust. Filing requirements differ, and who may appear on behalf of an owner is not always the owner.
- You own several parcels. Each PIN has its own assessment, its own township window and its own bill.
The deadline is the part people lose on
Cook County does not have one appeal deadline. It has a separate window for each of 38 townships, at each of two venues, and those windows open and close on their own schedule through the year. A township's Assessor window may close in June while its Board of Review window does not open until August.
A missed window generally cannot be reopened; in practice the remedy is the next available window. If both have passed for the year, that means carrying the assessment for another full cycle. In a reassessment year that assessment then carries forward for three years.
Check your township's current window before anything else. If it is open, the filing itself takes far less time than most people expect.
How an assessment becomes a tax bill
Three numbers produce your bill: the assessed value the Assessor placed on your property, the state equalization factor, and the local tax rate set by the taxing bodies where you live. You cannot negotiate the rate. The equalizer is set in Springfield. The assessed value is the only one of the three that can be challenged — and it is the one most likely to be wrong, because it is produced by a mass-appraisal model rather than by anyone visiting your property.
That is also why a successful appeal is worth more than one year's savings: the reduced assessment is the number that drives every subsequent bill until the next reassessment. See why Cook County bills rise and how assessed value differs from market value.
What an appeal cannot do
An appeal challenges your assessment, not your tax rate, not the equalizer, and not the total the taxing bodies levy. It does not pause a bill that is already due. And while increases are rare — across 2021 to 2025, roughly one in a thousand decided Cook County appeals ended in a higher assessment — they are not impossible, and anyone who tells you an assessment can only go down is overstating it.
Working with this firm
Cook County Tax Appeals is a contingency-fee practice: there is no upfront cost, and a fee arises only from a reduction actually obtained. We handle residential and commercial appeals at the Assessor and the Board of Review across all Cook County townships, and we are attorneys — the firm is led by an attorney who is also a CPA with an LL.M. in taxation.
Practical next steps:
- Confirm your township's window is open.
- Run your own numbers in the Cook County property tax calculator to see what a reduction would be worth on your parcel.
- Read how the appeal process runs end to end, and the signs that a property is over-assessed.
- If a reduction is granted after taxes have been paid, a refund may follow.
Deeper background on each venue: the Assessor's appeal process and the Board of Review.
