In tax year 2025 the Cook County Board of Review issued 366,001 decisions on attorney-filed residential appeals. Twenty attorney codes filed 244,659 of them, two in three. Their reduction rates ran from 18.5% to 57.7%. The median was 42.0%.
Every one of those decisions is in the Board's open data, PIN by PIN, with the filing attorney's code. A competing firm, a condo board choosing counsel or an owner with a portfolio can rebuild your firm's row in an afternoon.
Read it before they do.
Quick Answer
The Board publishes every decision as open data with the attorney code on the complaint. In tax year 2025 the 20 largest residential filer codes ranged from an 18.5% to a 57.7% reduction rate, median 42.0%. In 2024 the range was 14.3% to 53.5%, median 34.6%. From the same record anyone can rebuild a firm's wins, losses, township mix and market share. Pull your own first, and know what the rate does not measure.
The market in one table
Board decisions by tax year, all property classes:
- 2022: 469,007 decisions; 411,292 attorney-filed (87.7%); 395 active attorney codes.
- 2023: 406,396 decisions; 342,317 attorney-filed (84.2%); 379 active attorney codes.
- 2024: 571,841 decisions; 503,333 attorney-filed (88.0%); 367 active attorney codes.
- 2025: 523,042 decisions; 440,288 attorney-filed (84.2%); 372 active attorney codes.
Attorneys have filed between 81.2% and 89.2% of decisions in every tax year since 2010. The field is getting smaller: 482 codes filed in 2013, 372 in 2025.
It is also concentrated. Across 2023 through 2025, 483 codes filed at least once. The three largest filed 28.2% of attorney-filed decisions and the largest 20 filed 57.5%.
The spread among the biggest residential filers
For each year, the 20 codes with the most attorney-filed residential decisions:
- 2022: 335,758 attorney-filed residential decisions, 24.6% reduced. The top 20 codes ranged from 5.6% to 52.3% (median 27.8%).
- 2023: 267,259 decisions, 28.4% reduced. The top 20 ranged from 4.9% to 63.5% (median 34.3%).
- 2024: 422,245 decisions, 37.5% reduced. The top 20 ranged from 14.3% to 53.5% (median 34.6%).
- 2025: 366,001 decisions, 38.9% reduced. The top 20 ranged from 18.5% to 57.7% (median 42.0%).
In every year the gap between the highest and lowest large filer was wider than 39 percentage points. A prospect comparing two firms will see a gap of that size and ask about it.
Codes are attorneys, not firms. In 2025, 24 firm names filed under more than one code, and the 20 largest residential codes belonged to 18 firm names. Censum does not name firms next to rates, and neither should a pitch.
What anyone can rebuild about your firm
Realized wins. Reductions by tax year, township and class, and the assessed value removed: the Assessor's value minus the Board's, on every decision.
Losses, and why. Each no-change decision carries a reason code. In the current copy of the data, 100,458 attorney-filed decisions from 2023 through 2025 carried one of two paperwork codes: 68,212 for no documentation beyond the complaint form and 32,246 for failure to comply with Board rules or requests. Censum's September count of 86,107, in an earlier version of the paperwork article, used the May copy, before tax year 2025 had filled in.
Share. Your decisions as a share of attorney-filed decisions in each township and class, year over year. Share that slips in a reassessment year is worth a look.
Mix. Condo, single-family, multi-family and commercial files behave differently, and the record shows which ones you file.
Why the spread is not a ranking
The rate is easy to quote and easy to misread.
- Mix drives it. Township and class move rates more than most firms expect. A book heavy in a township where the Board rarely cuts condos will show a low rate however good the files are. See condo reduction rates by township.
- Selection drives it. A firm that files only its strongest cases will beat one that files every client.
- Counts are PIN-level. One association engagement can produce hundreds of decisions.
- Reductions are assessed value. Dollars depend on the equalizer, exemptions and each tax code's rate.
- The reassessed region moves the numbers. 2024 was Chicago's reassessment year and 2025 the north suburbs'. Compare like years.
Read your own row in 30 minutes
- List every code. Every attorney at the firm, plus predecessor firms and name variants.
- Pull three tax years. 2023 through 2025, filtered on those codes.
- Cut it by township and class. Compute the rate per cell, not just overall.
- Split the losses. Merits losses on one side, paperwork codes on the other.
- Check share. Your share of attorney-filed decisions in each township against the prior cycle.
- Write the explanation for your weakest cell now.
Most firms find at least one township where share fell and one batch of files that never reached the merits.
When a prospect brings your number
- Start with the cell that matters to them: their township and their class.
- Explain mix and selection with your own numbers, not adjectives.
- Name the paperwork losses and what the firm changed.
- Do not promise a rate. A historical rate is history, not a forecast.
Where Censum Docket fits
Docket's win intelligence shows realized Board outcomes by township and the market share and win rates of every firm, reconstructed from the public record, and flags when a competitor files on one of your clients. Results & ROI attributes your realized reductions from the same record. A Docket demo starts from your own results, because they are already public.
Censum is not a legal referral service and never takes a share of legal fees. Docket does not file appeals or appear before the Board. Your firm keeps the client, the judgment and the filing.
The numbers behind this article
All counts are Censum's tabulation of the Board's Appeal Decision History dataset on Cook County's open data portal, accessed November 7, 2026. They are PIN-level decisions, not complaints, and should not be compared with the Board's own "appeals" totals. Every township shows 2025 decisions at levels in line with its prior cycle, so 2025 appears complete; late decisions can still post. "Attorney-filed" means the dataset's attorney code field reads "Attorney". "Reduced" means a result of "Decrease".
Sources
- Censum tabulation of the Cook County Board of Review Appeal Decision History dataset (Cook County open data), accessed November 7, 2026; PIN-level decisions.
- Cook County Board of Review Official Rules, last updated July 27, 2026.
FAQ
What was the range among the 20 largest residential filers?
In tax year 2025, 18.5% to 57.7% reduced, median 42.0%, across the 20 codes with the most attorney-filed residential decisions. In 2024, 14.3% to 53.5%, median 34.6%.
Is it appropriate to analyze another firm's filings?
The decisions are public records about parcels, published by the Board. Analyzing them is market research. How you use the information is governed by the same professional rules as any other outreach.
Can a firm keep its results out of the record?
No. The Board publishes decisions as open data.
Does the record show client names?
Each decision row carries the PIN and an appellant field as filed. Censum works from PINs and does not publish appellant names. Matching the record to a client book still requires your own PIN list.
How current is the data?
In the county's copy accessed November 7, 2026, tax year 2025 appeared complete and no 2026 decisions had posted. Decisions for each year post over months after the township's hearings, so check the dataset's last-updated date before you count.
Does Censum file or represent clients?
No. Censum LLC is independent property-tax intelligence and docket tooling. It is not a law firm. The attorney files and makes every legal judgment.
Next step
Pull your firm's 2023 through 2025 decisions by code, township and class, and write down the explanation for your weakest cell. See Docket's win intelligence
Censum LLC is independent and not affiliated with Cook County or any government agency.