Tax Assessment Appeal Success Rate: Cook County BOR Data by Township (2024)

Across 57,960 commercial Board of Review appeals filed in Cook County for tax year 2024, the overall tax assessment appeal success rate was 37.5% — meaning roughly 1 in 3 appeals received some reduction. When successful, the average reduction was 21.5% off the Assessor's value. But township-level success rates vary from under 20% to over 70%, driven heavily by whether that township was reassessed that year.

"What are my odds?" is the first question every commercial property owner asks before filing a tax appeal. The honest answer: it depends massively on which township your property sits in — and on whether your township was just reassessed.

We analyzed all 57,960 commercial and industrial Board of Review appeals filed in Cook County for the 2024 tax year — straight from the Assessor's open data portal. The results show two clear patterns: average BOR reductions ranged from under 2% in some townships to over 17% in others, and the highest-grant townships were almost all in the City of Chicago — because 2024 was the Chicago triennial reassessment year, and reassessment years produce dramatically more BOR activity.

Here's what the data shows.

The Headline Numbers (2024 Tax Year)

Metric	2024 BOR Commercial Appeals
Total appeals filed	57,960
Appeals with any reduction	37.5% (21,710)
Appeals with 10%+ reduction	25.2%
Appeals with 25%+ reduction	13.8%
Average reduction across all appeals	8.04%
Average reduction when successful	21.5%
Total assessed value reduced	$4.36 billion

So roughly 1 in 3 commercial BOR appeals get some reduction, and 1 in 4 get a meaningful (10%+) reduction. The successful ones average just over 21% off the Assessor's number — and across the whole population of appeals, the BOR cut $4.36 billion of assessed value off Cook County's commercial roll in a single tax year.

The Top 10: Chicago Townships Dominate Reassessment Years

The 2024 reassessment year was the City of Chicago's turn in the triennial cycle. Every commercial property in Chicago received a new assessed value, owners filed appeals in volume, and the BOR granted reductions at rates not seen elsewhere in the county that year. Eight of the top 10 townships by average reduction are Chicago townships:

Township	Triad	Appeals	% That Won	Avg Reduction	Avg When Won
North Chicago	Chicago	2,816	61.1%	17.1%	28.0%
South Chicago	Chicago	4,509	70.2%	15.6%	22.3%
Rogers Park	Chicago	740	64.6%	13.8%	21.4%
Hyde Park	Chicago	2,935	58.2%	13.2%	22.7%
West Chicago	Chicago	4,375	55.3%	12.7%	22.9%
Jefferson	Chicago	7,465	56.7%	10.6%	18.7%
Lake View	Chicago	2,762	48.7%	9.8%	20.1%
Lake	Chicago	7,018	51.7%	9.3%	18.1%
Calumet	South/SW	226	13.7%	5.5%	41.5%
Oak Park	South/SW	388	25.0%	5.3%	21.3%

Two things stand out in this top 10. First, South Chicago had the highest win rate in the entire county at 70.2% — more than 7 in 10 commercial appeals received a reduction. Second, North Chicago had the highest average reduction at 17.1%, with 61% of appeals winning and an average reduction of 28% when they won.

Volume is concentrated too: Jefferson Township alone produced 7,465 commercial BOR appeals — roughly 13% of the county's entire commercial BOR docket from a single Chicago township. Lake (7,018), South Chicago (4,509), and West Chicago (4,375) round out the high-volume group.

The Bottom 10: Non-Reassessment Years Are Rough

Townships not being reassessed in 2024 — the north and south/west suburban triads — show dramatically lower win rates and average reductions. Filtering to townships with at least 100 commercial appeals:

Township	Triad	Appeals	% That Won	Avg Reduction	Avg When Won
New Trier	North/NW	267	13.5%	1.6%	11.7%
Lyons	South/SW	1,803	7.5%	1.6%	21.7%
Elk Grove	North/NW	813	7.5%	1.7%	22.5%
Hanover	North/NW	474	7.0%	1.9%	27.1%
Wheeling	North/NW	1,738	9.7%	2.0%	20.5%
Palos	South/SW	486	8.4%	2.0%	23.9%
Berwyn	South/SW	409	9.8%	2.0%	20.8%
Worth	South/SW	2,061	8.8%	2.1%	23.3%
Maine	North/NW	970	11.3%	2.3%	19.9%
Norwood Park	Chicago	257	12.5%	2.3%	18.2%

Lyons, Elk Grove, and Hanover all sit at roughly 7-8% win rates with average reductions under 2%. That's a fundamentally different filing environment than the Chicago townships. Same evidence quality, ten-fold worse outcomes — entirely because of where the property sits in the reassessment cycle.

Three Patterns That Matter for 2026 Appeals

1. Reassessment year dominates everything

The single strongest predictor of BOR success in our 2024 data isn't case quality, attorney, or property type — it's whether the township was being reassessed. Every Chicago township ranks in the top 10. Every non-reassessment township ranks lower regardless of its long-term reputation.

What this means for 2026: The south and southwest suburbs are being reassessed this year. Based on the 2024 Chicago pattern, expect BOR win rates in those townships to climb substantially this cycle compared to 2024 levels. Properties in Bloom, Bremen, Cicero, Oak Park, Orland, Palos, Proviso, Rich, River Forest, Riverside, and others have the best appeal economics this year that they'll see until 2029.

2. The "win when won" gap is narrow — but the "did you win" gap is enormous

Look at the avg when won column. Across both top and bottom townships, when the BOR grants a reduction, it's typically 18–28%. The Cook County BOR, when it grants a reduction, grants a similar-sized reduction regardless of township.

The variation is almost entirely about whether you get a reduction at all, not how big it is. So the strategic insight: filing into a reassessment-year docket is fundamentally different from filing in an off-year docket, even with identical evidence.

3. Off-year appeals still work — they just need stronger evidence

An 8% win rate in Lyons isn't zero — it's 1 in 12. With contingency-fee structures, the math still works on a strong case. But weak appeals in off-year townships fail almost universally. The bar is just higher.

What This Means for Your Appeal Strategy

If your property is in a 2026 reassessment township (south/west suburbs): File. The reassessment-year tailwind is real, this is your best window for the next three years, and your evidence work compounds with the BOR's increased willingness to grant reductions during reassessment cycles.

If your property is in Chicago or the north suburbs: 2024 was Chicago's reassessment year and 2025 was the north's — those windows are now closed. Your annual appeals still work, but expect 2026 results closer to the historical bottom-10 numbers. You need stronger evidence.

If you have multiple properties across townships: Prioritize evidence work and budget toward the reassessment-year townships first. The cost-of-effort to expected-savings ratio is dramatically better there.

Caveats and Limitations

• This is BOR data, not Assessor-level data. Many appeals get reductions at the Assessor level and never reach the BOR. The data we analyzed represents cases where the Assessor either denied a reduction or where the property owner chose to escalate further.
• Win rates depend on case quality. A 70% township win rate doesn't mean any random filing will win 70% of the time. Strong evidence still matters. Weak appeals fail in every township.
• Past performance is not a guarantee. The CCAO's methodology evolves. 2026's loaded cap rate change, expanded vacancy categories, and tightened evidence rules may shift outcomes.

How TaxRival Can Help

We track every Cook County commercial property's assessment against comparable sales and income data. Enter your 14-digit PIN on our homepage and we'll show you whether your property appears over-assessed and what a successful appeal could save you — given the township-specific success rates above and the 2026 reassessment cycle.

Our fee is 25% of first-year tax savings, on contingency. If we don't reduce your assessment, you pay nothing. The data above informs which cases we take and how aggressively we pursue them — we want to win.

Source: Cook County Assessor's Office open data portal, dataset 7pny-nedm (Board of Review Appeal History). Analysis covers commercial and industrial appeals filed for tax year 2024. Township is the official CCAO township_code field. Data accessed April 2026.