Cook County appeal evidence
How to find comparable sales for a Cook County property tax appeal
A useful comparable sale is not simply the cheapest nearby property. It is a recorded sale of a property that resembles yours closely enough to make the price meaningful evidence.
By Check the County, operated by Embento LLC. Updated September 19, 2026. This is general public-record research information, not legal, tax or appraisal advice.
Verify your property record first
Before searching for sales, check the Assessor's record for your property. Confirm its assessment neighborhood, property class and type, building size, age, lot characteristics and other relevant facts. If the starting facts are wrong, a search based on them can produce poor comparisons.
Keep the property type consistent. Do not mix a single-family home with a two- to six-flat or a condominium. Those are different types of property and should not be treated as interchangeable sales evidence.
What makes a sale comparable?
Look first within the same assessment neighborhood and property class or type. Then compare building size, age, lot characteristics and how recently each property sold. No one characteristic decides the answer; the closer the overall match, the easier it is to explain why the sale is relevant.
Price alone is not enough. A low-priced property may be much smaller, older, on a different lot, or unlike your property in another material way. A sale can be nearby and still be a weak comparable.
Check whether the sale itself is unusual
A family transfer, distressed transaction or sale of a heavily renovated property may not reflect the same market circumstances as an ordinary sale of a similar home. Review the public record and the property facts you can verify before relying on an unusual transaction.
If you cannot confirm why a sale is unusual, do not guess. Describe only what the records support and follow the receiving office's current evidence instructions.
Do not confuse two per-square-foot measures
Sale price per square foot divides a recorded sale price by building area. Assessed value per square foot divides an assessed value by building area. They answer different questions and should not be compared as though they were the same measure.
What if there are few recent sales?
Use the closest supportable matches available without mixing property types or hiding important differences. Review the county's current instructions, explain relevant limitations in the evidence, and avoid overstating what a small or imperfect set of sales proves.
Find your township guide for local context, or start with the broader Cook County property tax appeal research guide.