Across tax years 2023 through 2025, the Cook County Board of Review issued 1,268,859 PIN-level decisions on residential property and reduced 39.2 percent of them. By township, the rate ran from 53.1 percent in Cicero and 52.7 percent in Schaumburg down to 21.5 percent in South Chicago township.
Those are public records of where the Board most often cut the home assessments it was asked to review. Farm selection usually comes down to turnover and price. This is a third number, and it gives you something worth saying to owners who are not selling yet.
Quick Answer
From 2023 through 2025 the Board reduced 39.2% of residential decisions county-wide, from 53.1% in Cicero to 21.5% in South Chicago township. Add that record to the usual farm math of turnover and price band, then time the farm to the area's reassessment year, when each region's reduction rate ran highest in the latest cycle. Use it to start conversations with dates and free checks. Segment only on property facts, never on owners.
The usual farm math
The standard screen still matters:
- Turnover: the share of homes that sell each year
- Price band: the commission each sale is worth
- Competition: how many agents already work the area
What that screen does not give you is a reason to talk to anyone before they are ready to sell.
Where reductions cluster
Residential PIN-level decisions, tax years 2023 through 2025 combined. Every township's own reassessment year falls inside this window, so each rate covers one full cycle.
Highest reduction rates:
- Cicero: 6,430 decisions, 3,417 reduced (53.1%)
- Schaumburg: 36,841 decisions, 19,427 reduced (52.7%)
- Hanover: 21,118 decisions, 10,718 reduced (50.8%)
- Norwood Park: 7,929 decisions, 3,930 reduced (49.6%)
- Berwyn: 9,818 decisions, 4,835 reduced (49.2%)
Lowest reduction rates:
- South Chicago township: 92,348 decisions, 19,891 reduced (21.5%)
- North Chicago township: 122,730 decisions, 28,103 reduced (22.9%)
- Evanston: 25,881 decisions, 8,313 reduced (32.1%)
- Rogers Park: 19,189 decisions, 6,604 reduced (34.4%)
- Hyde Park: 27,680 decisions, 9,978 reduced (36.0%)
South Chicago and North Chicago are townships inside the City of Chicago, not the suburbs with similar names.
By region over the same years: north suburbs 45.1%, south and west suburbs 43.4%, City of Chicago 33.5%.
Read the volume with the rate. Schaumburg's 19,427 reductions in three years is a different farm from Cicero's 3,417, even at the same rate.
The reassessment year multiplies it
The three-year totals hide how lopsided the cycle is. In the north suburbs' 2025 reassessment year:
- Hanover: 69.0% of 12,119 residential decisions reduced, up from 26.1% in 2023.
- Schaumburg: 68.5% of 21,707, up from 31.5%.
- Elk Grove: 62.6% of 16,389, up from 28.7%.
Cook County reassesses one region a year:
- 2026: south and west suburbs
- 2027: City of Chicago
- 2028: north suburbs
- 2029: south and west suburbs again
A farm in next year's reassessment region gives you a natural, timely reason to show up. For 2027, that is Chicago.
What the rate does and does not tell you
A reduction rate counts only homes whose owners appealed. It says how often the Board agreed with those owners. It does not say how many homes in the township are over-assessed, and it says nothing about any single home.
Use it to choose where to look. Then look at the homes.
Which signals to look at
- Homes assessed above comparable homes, a possible uniformity issue
- Homes assessed above what similar homes recently sold for, a possible value issue
- Missing exemption lines on the record
- Recent sales that diverge from assessments on the same block or in the same building
- Improvements that are permitted but not yet reflected in the assessment, a directional sign the value may rise
Treat every one as a signal to check, not a claim. Some flagged homes are assessed correctly.
How to read density
Look for concentration, not totals:
- The share of homes flagged on a block or in a subdivision
- The typical dollar value of the flags
- How recent the underlying sales and records are
- Condo buildings where several units show the same pattern
Leave out entity-owned parcels. They need a different conversation.
Combining the lenses
High turnover and high density: the strongest farm. Owners move often and you have a reason to talk to them now.
High density, low turnover: a long game. Owners stay put, but you can become their tax resource for years.
High turnover, low density: a conventional farm. Tax signals will not add much.
Low on both: skip it.
Stay fair-housing clean
Segment only on property, township and timing facts. Never build a list on owner age, family status, race, national origin, disability, or anything that stands in for them. Do not create a "senior" list to market senior exemptions. Tell everyone about every exemption, and let owners decide what applies.
What to say
- "Your township's appeal window opens next month. Here's the official calendar."
- "Several homes on your street show a missing exemption on the county record. Here's how to check yours."
- "Your area is reassessed next year. Here's what the notice will and won't mean."
Each one is a fact, a date or a free check. None says a specific home is over-assessed.
Where Censum House fits
Censum House's Intel Harvest ranks townships by the density of over-assessment candidates and lets managers assign blocks to agents. Gift-Farm shows where giftable exemption filings cluster, and Reassessment Radar flags homes with improvement permits not yet captured. Your ROI tracks which flags led to conversations and deals.
The numbers behind this article
Decision counts and rates are Censum's tabulation of the Cook County Board of Review Appeal Decision History dataset (county open data, 7pny-nedm), last updated by the county on June 9, 2026. They are PIN-level residential decisions, including condominium units, not complaints. Township names and regions follow the Assessor's records. Censum is independent and is not affiliated with Cook County or any government agency.
FAQ
Which Cook County townships had the highest residential reduction rates?
From 2023 through 2025: Cicero 53.1% of 6,430 decisions, Schaumburg 52.7% of 36,841, and Hanover 50.8% of 21,118. The lowest was South Chicago township, 21.5% of 92,348.
Is it okay to mail owners about their property taxes?
Yes, with factual, property-based content and your brokerage's required disclosures.
Should I tell an owner their home is over-assessed?
No. Say it may be worth checking, and point them to a free check or the official record.
Does high density mean owners will sell?
No. It means you have a useful reason to talk to them. Selling is a separate decision.
How often should I refresh the data?
At least each time new notices or bills go out, and before each campaign.
Sources
- Cook County Assessor, Assessment Calendar and Deadlines
- Cook County Assessor, Property Tax Exemptions
- Cook County Clerk, Tax Extension and Rates: 2025 Tax Rate Report, which states Chicago's next reassessment is for tax year 2027
- U.S. Department of Housing and Urban Development, Fair Housing and Equal Opportunity
- Censum tabulation of the Cook County Board of Review Appeal Decision History dataset (Cook County open data), accessed November 7, 2026; PIN-level decisions; dataset last updated June 9, 2026.
Next step
Pick the two or three townships you are weighing, compare their reduction record and reassessment year, then see which blocks have the most to talk about. See Intel Harvest in Censum House
Censum LLC is a data and analytics company, not a law firm and not a tax advisor. Censum is independent and is not affiliated with Cook County or any government agency.