Comparable Properties vs. Comparable Sales: Cook County Appeal Evidence Explained
When people search for “comparable sales” for a Cook County property tax appeal, they often mean two different things. Understanding the distinction matters — and knowing which type of data TaxedTooMuch actually provides will help you use it correctly.
What TaxedTooMuch provides: uniformity evidence
TaxedTooMuch is an informational data service. Our report shows your assessed value per square foot compared to comparable assessed properties in the same CCAO neighborhood — not market sales transactions. This is the data that supports a lack of uniformity appeal basis. What you do with this information, whether to file, and any legal questions are entirely your responsibility.
The two types of evidence in a Cook County appeal
Cook County appeals generally rely on one or both of these evidence types:
1. Comparable Sales (Market Value)
Recent arm's-length sale prices of similar nearby properties. The argument: your home would sell for less than your assessment implies.
- · Based on actual sale transactions
- · Requires recent sales in your area
- · Found in deed records and CCAO sales data
- · You must gather and organize this yourself
2. Uniformity Evidence (Assessment Comparison)
Assessed values of comparable neighboring properties. The argument: similar properties nearby are assessed at a lower rate per square foot.
- ✓ Based on CCAO assessment records
- ✓ Works even in low-turnover neighborhoods
- ✓ No appraisal needed
- ✓ This is what TaxedTooMuch provides
What's actually in a TaxedTooMuch report
A TaxedTooMuch data report is built entirely from Cook County Assessor's Office open public records. It does not use market sales data. Here's what it contains — and what it does not:
Your property profile
Address, PIN, township, property class, year built, building square footage, bedrooms/bathrooms, exterior construction, garage.
Assessment breakdown
Land assessed value, building assessed value, total assessed value, and building assessed value per square foot (the core comparison metric).
Comparable assessed properties
Up to 5 or more neighboring properties from the same CCAO neighborhood, same property class, and similar square footage and year built — each with their full assessment breakdown and $/sqft rate.
Summary comparison table
Your $/sqft rate side by side with each comparable — making the uniformity gap visible at a glance.
Uniformity gap calculation
The difference between your $/sqft rate and the average comparable rate, plus an implied fair building assessment based on that gap.
BOR filing information
Informational guidance on the Board of Review process, deadlines, and where to contact the BOR directly (312-603-5542, cookcountyboardofreview.com).
How the uniformity calculation works
The report compares your building assessed value per square foot to the average of comparable properties in the same CCAO neighborhood. Here's how to read it:
Example data from a TaxedTooMuch report
Illustrative data from an actual report. Not legal advice. All figures are informational estimates only and do not guarantee any appeal outcome or savings. Consult a licensed attorney with any legal questions.
If you also want comparable sales data
TaxedTooMuch does not provide market sales data — but you can find it yourself from public sources if you want to supplement a uniformity filing with sales evidence:
CCAO Open Data Portal
datacatalog.cookcountyil.gov
The Cook County Assessor publishes arm's-length sales data in its public datasets. Free to access. Requires filtering by neighborhood, property class, and date range.
Cook County Recorder of Deeds
cookcountyil.gov/recorder
Deed transfer records include sale prices and dates for every recorded Cook County transaction. Useful for confirming recent sales and arm's-length status.
Frequently asked questions
Does TaxedTooMuch provide comparable sales data?
No. TaxedTooMuch provides a uniformity analysis — comparing your assessed value per square foot to comparable assessed properties in the same CCAO neighborhood. This is informational data to support a lack-of-uniformity basis. It is not a market sales report, not legal advice, and not an appraisal.
What's the difference between uniformity evidence and comparable sales?
Comparable sales are recent market transactions showing what homes like yours actually sold for. Uniformity evidence compares your assessed value to how similar neighboring properties are currently assessed — no sales needed. TaxedTooMuch provides the latter.
Do I need an appraisal to use the TaxedTooMuch report?
No. The report is based on public CCAO assessment data and does not require an appraisal. For any questions about what evidence is appropriate for your specific situation, consult a licensed attorney or contact the Board of Review directly at 312-603-5542.
What if I want to use both uniformity evidence and comparable sales?
Many homeowners choose to gather both types of evidence. The TaxedTooMuch report provides the uniformity portion. You would need to gather market sales data separately from CCAO open data or the Recorder of Deeds. What you submit and how is entirely your decision — TaxedTooMuch does not file appeals or provide filing guidance.
About TaxedTooMuch (TTM)
TTM (TaxedTooMuch) is an informational data service. Not a law firm. Not legal advice. Not a tax advisor or appeal service. All estimates are for informational purposes only and do not guarantee any savings or appeal outcome. TaxedTooMuch provides data only — you are solely responsible for any appeal you choose to file, the evidence you choose to use, and consulting a licensed attorney or tax professional for guidance on your specific situation.
Continue reading
Cook County Appeal Guide 2026 →
Step-by-step walkthrough of the full appeal process
Uniformity Appeals Explained →
How the uniformity argument works — and what data it requires
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