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Cook County, Illinois
over 400,000
Cook County homes
are over-assessed.
That's an estimated $2.1 billion in excess assessed value — based on public data, many homeowners may not know their assessment is higher than comparable properties.
The average over-assessed Cook County home carries $5,137 in excess assessed value — roughly $1,387/year in estimated excess taxes.
Check if your home is one of them — freeHere's what you'll see for free
Your assessed value
$24.10 / sq ft
Neighborhood average
$18.40 / sq ft
14 comparable properties
Your assessed value is $5.70/sq ft above comparable properties.
Estimated assessment difference: $14,820 · Estimated annual difference: $1,200–$2,400/yr (est.)
Comparable properties are hidden
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How it works
Enter your address
We look up your property in the Cook County Assessor database and calculate your assessed value per square foot.
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We show you how your $/sq ft compares to similar properties in the same CCAO assessment neighborhood — for free.
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Pay $49. Review your comparable properties and estimated assessment differences in a comprehensive informational data report.
Why a uniformity appeal?
Most appeal services argue your home is worth less than its assessed value — which requires an appraisal and sales data. The Cook County Board of Review also accepts uniformity appeals: presenting data that comparable properties are assessed at a lower rate per square foot.
We use real Cook County Assessor data — the same public data the Board of Review has access to — to provide a comparable property analysis for your property.
Learn more about uniformity vs. overvaluation appeals →Methodology & Sources
Data source
Cook County Assessor's Office open data portal. Tax year 2024 residential parcels (classes 200–299). 1,090,975 properties analyzed.
datacatalog.cookcountyil.gov →Definition of over-assessed
A property is over-assessed if its assessed building value per sq ft exceeds the average of comparable properties in the same CCAO assessment neighborhood, property class, and size range by more than $0.50/sq ft. This is a conservative threshold.
Tax savings estimate
Excess assessed value is multiplied by an effective rate of 27% — derived from Cook County's assessment level (~10% of market value), state equalization factor (~3×), and composite levy rate (~9.7%). Actual savings vary by township and tax code.
Analysis date: 2026-03-31