Who actually wins a Cook County property tax appeal
Cook County homeowners who filed their own Board of Review appeal for tax year 2025 got their assessment cut 51.3% of the time. Homeowners who filed through a lawyer or tax agent got a cut 39.5% of the time.
The gap holds at both levels, in all three tax years we hold, and in 35 of the 38 townships with enough appeals to measure. It is not evidence that hiring an agent hurts you — read the method and the limits before quoting it.
of self-filed residential Board of Review appeals were decreased, 2023–2025 (276,525 appeals)
of attorney-filed residential Board of Review appeals were decreased (992,334 appeals)
of self-filed Assessor appeals changed the value (199,481 appeals), against 16.9% of agent-filed ones
of the Assessor reductions we hold carry the same single boilerplate reason line
Residential appeal outcomes, self-filed against represented
Cook County residential property (class 2, including condominium units). An Assessor appeal counts as a win when the Assessor's own record says the value changed; a Board of Review appeal counts as a win when its recorded result is “Decrease”.
| Tax year | Assessor · self-filed | Assessor · agent filed | Board of Review · self-filed | Board of Review · attorney filed | ||||
|---|---|---|---|---|---|---|---|---|
| Appeals | Changed | Appeals | Changed | Appeals | Decreased | Appeals | Decreased | |
| 2023 | 59,395 | 23.1% | 156,989 | 17.9% | 75,973 | 54.2% | 254,871 | 28.1% |
| 2024 | 71,794 | 20.8% | 329,053 | 18.9% | 93,734 | 50.7% | 396,497 | 37.3% |
| 2025 | 68,292 | 18.4% | 267,623 | 13.8% | 106,818 | 51.3% | 340,966 | 39.5% |
“Self-filed” means the county's own file records no agent (Assessor field agent_name) or no attorney firm (Board of Review field attorney_firm_name) on the appeal. No share is printed from fewer than 100 appeals.
The gap by township, tax year 2025
Board of Review residential appeals, ranked by how many percentage points more often a self-filed appeal was decreased than an attorney-filed one in the same township and year.
| Township | Self-filed appeals | Decreased | Attorney-filed appeals | Decreased | Gap (points) |
|---|---|---|---|---|---|
| Lake View | 1,355 | 46.6% | 20,251 | 20.1% | +26.5 |
| Cicero | 1,209 | 58.6% | 639 | 33.0% | +25.6 |
| Evanston | 1,992 | 58.0% | 11,075 | 32.7% | +25.3 |
| Jefferson | 8,059 | 59.5% | 20,036 | 35.3% | +24.2 |
| Riverside | 329 | 52.9% | 799 | 29.8% | +23.1 |
| Worth | 2,658 | 50.4% | 3,677 | 27.4% | +23.0 |
| Calumet | 336 | 51.5% | 288 | 29.5% | +22.0 |
| Oak Park | 1,531 | 51.9% | 2,552 | 30.3% | +21.5 |
| Proviso | 3,403 | 50.0% | 3,580 | 29.4% | +20.7 |
| Maine | 4,061 | 64.2% | 21,253 | 44.9% | +19.2 |
| Lake | 9,986 | 56.3% | 5,355 | 37.2% | +19.1 |
| Rogers Park | 542 | 41.7% | 3,498 | 22.9% | +18.8 |
| Leyden | 2,806 | 65.6% | 6,536 | 47.4% | +18.3 |
| Lemont | 685 | 42.2% | 1,369 | 24.7% | +17.5 |
| Hyde Park | 3,389 | 38.5% | 6,201 | 21.3% | +17.3 |
| River Forest | 229 | 51.1% | 1,009 | 34.5% | +16.6 |
| Stickney | 743 | 51.5% | 959 | 35.8% | +15.8 |
| Bloom | 1,678 | 48.5% | 1,333 | 33.6% | +14.8 |
| Berwyn | 1,851 | 46.5% | 1,173 | 32.1% | +14.4 |
| Elk Grove | 2,521 | 74.3% | 13,868 | 60.4% | +13.8 |
| Norwood Park | 946 | 67.8% | 2,909 | 54.0% | +13.8 |
| Palatine | 3,901 | 68.5% | 18,877 | 54.8% | +13.7 |
| New Trier | 1,892 | 62.1% | 12,830 | 48.8% | +13.3 |
| Bremen | 2,414 | 43.6% | 3,041 | 30.4% | +13.3 |
| Lyons | 2,820 | 43.7% | 4,552 | 30.7% | +13.0 |
| Wheeling | 6,356 | 63.2% | 26,308 | 50.3% | +12.9 |
| South Chicago | 3,434 | 27.3% | 22,140 | 14.7% | +12.7 |
| Barrington | 559 | 61.5% | 2,920 | 49.7% | +11.8 |
| West Chicago | 6,682 | 34.5% | 18,394 | 23.5% | +10.9 |
| Palos | 1,495 | 34.7% | 2,130 | 23.9% | +10.8 |
| Niles | 2,940 | 64.7% | 17,449 | 54.8% | +9.9 |
| Orland | 2,563 | 39.1% | 4,629 | 29.8% | +9.3 |
| Thornton | 4,780 | 45.7% | 2,718 | 36.6% | +9.1 |
| Rich | 2,538 | 41.6% | 1,681 | 33.1% | +8.5 |
| Northfield | 2,780 | 60.8% | 19,631 | 56.8% | +4.0 |
| Hanover | 2,684 | 64.5% | 9,435 | 70.3% | -5.8 |
| North Chicago | 3,629 | 2.3% | 29,206 | 13.8% | -11.4 |
| Schaumburg | 5,042 | 57.1% | 16,665 | 71.9% | -14.8 |
38 of Cook County's 38 townships had at least 100 residential appeals on both sides in tax year 2025. 3 townships run the other way: Hanover, North Chicago, Schaumburg — those are in the table too, at the bottom.
How this was computed
- Every row of the Cook County Assessor's Appeals file and the Board of Review's Appeal Decision History file is loaded in full; row counts are reconciled against the publisher's own count before a load is accepted.
- Rows are kept for residential classes only — class 2xx. The Board of Review file writes the class as five digits (29900) for 2022–2023 and three (299) from 2024, so it is divided down before the range test.
- Assessor rows are kept only where the status begins “closed” and a change value is recorded; Board of Review rows only where a result is recorded.
- An appeal is “self-filed” where the county's file records no agent name (Assessor) or no attorney firm name (Board of Review), and “represented” where it records one.
- Shares are simple counts: wins ÷ appeals, per year, per level, per representation. No weighting, no modelling, no exclusions beyond the ones above.
The SQL is the same query the page is built from, so the figures cannot drift from the text:
SELECT tax_year,
(attorney_firm_name IS NOT NULL AND btrim(attorney_firm_name) <> '') AS represented,
count(*), count(*) FILTER (WHERE result = 'Decrease')
FROM property.bor_appeals
WHERE jurisdiction = 'IL-Cook' AND tax_year = ANY(%(years)s) AND result IS NOT NULL
AND (CASE WHEN class >= 1000 THEN class / 100 ELSE class END) BETWEEN 200 AND 299
GROUP BY 1, 2 ORDER BY 1, 2Citation
CivicDelta, “Cook County residential tax appeals: owners who filed alone won more often than agent-filed appeals, 2023–2025”, computed from Cook County Assessor dataset y282-6ig3 and Board of Review dataset 7pny-nedm.
Retrieved from civicdelta.com/research/cook-county-appeal-representation/. Figures on this page are recomputed whenever the underlying county files are reloaded; the capture dates below say which load they came from.
Dataset: Cook County residential appeal outcomes by representation, 2023–2025 · temporal coverage 2023/2025 · spatial coverage Cook County, Illinois · last rebuilt 2026-09-28.
The one-sentence finding: Cook County homeowners who filed their own Board of Review appeal for tax year 2025 got their assessment cut 51.3% of the time. Homeowners who filed through a lawyer or tax agent got a cut 39.5% of the time.
Sources and capture dates| 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 Assessor and Board of Review open data, retrieved through the county's Socrata API on the dates shown.
What this does not tell you
- It is not causal. Nobody is randomly assigned an agent. Agents file at volume across whole neighborhoods, including weak cases they were never going to win; an owner who files alone has usually decided their own case is worth the effort. Selection alone could produce the whole gap.
- It says nothing about the size of the cut. Only whether the recorded result was a decrease. A represented appeal that wins a larger reduction counts here exactly the same as a self-filed one that wins a small one.
- It does not price the agent. A contingency-fee agent who wins less often but costs nothing up front can still be the right choice; this page cannot tell you that.
- Hanover runs the other way. The gap is not a law of nature. Look at your own township's row before using the county-wide figure.
- It covers residential property only, in Cook County only, for the tax years we hold — and appeals beyond the Board of Review (the Illinois Property Tax Appeal Board, or the circuit court) are not in either file.
- The Assessor rarely says why. 154,814 of the 168,517 residential reductions we hold (91.9%) carry the identical reason line — “This is a result of a market analysis of your property as well as an analysis of comparable properties.” — so this data cannot tell you which arguments worked.
None of this is legal or tax advice, and CivicDelta does not file appeals. If you want to see how your own home compares with near-identical homes nearby, the free check does that, and the Tax Appeal Evidence Packet assembles the comparables into a filing-ready document.
Questions people ask
Does hiring a tax appeal lawyer make you less likely to win in Cook County?
The county's own records show a lower success rate on represented appeals — 35.7% against 51.9% for self-filed ones at the Board of Review, 2023–2025 — but that is a comparison of different appeals, not the same appeal filed two ways. Agents file in bulk, including cases an owner would not have bothered with. The honest reading is that filing without an agent is clearly not hopeless, not that an agent hurts.
Which stage of a Cook County appeal is more likely to reduce an assessment?
The Board of Review. Across 2023–2025, 51.9% of self-filed residential Board of Review appeals were decreased, against 20.7% of self-filed Assessor appeals that changed a value. The Board is a separate, second appeal, and you can file it whether or not the Assessor changed anything.
Is it free to appeal your own Cook County assessment?
Filing an appeal with the Cook County Assessor and with the Cook County Board of Review costs nothing. Both take filings online, in windows that open township by township — see the Assessor's calendar and the Board of Review's residential appeals page, and our step-by-step guide.
How many residential appeals does Cook County decide?
In the three tax years on this page the county's files record 953,146 closed residential appeals to the Assessor and 1,268,859 residential decisions at the Board of Review.
Can I reuse these numbers?
Yes — the underlying files are Cook County open data and the computation is described in full above. Please cite the page and the capture date, because the figures are recomputed whenever the county files are reloaded.