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Blog · Evidence · 2026-08-03 · 2 min read

How to find comparable properties for a tax appeal

Start from the county's own records, not from what you know about the neighbourhood.

The instinct is to think of houses you know. Resist it. A comparable you chose because you like the street is one the assessor can dismiss, because "my neighbour" is not an attribute anyone recorded.

Work from the record

Open your county's parcel search and find properties that match yours on the fields the county publishes: property class, township or town, lot size, building size, year built. Those are the attributes the assessment was built from, so a match on them is a match the assessor cannot easily argue with.

The order to filter in

  1. Same class code. Non-negotiable — different classes are assessed differently.
  2. Same town, ideally same neighbourhood code.
  3. Lot size within about 10%.
  4. Building size within about 10%, where the county publishes one.
  5. Year built within a decade.

Then check the assessments

Compute assessed value per square foot for each — of building where you have it, of land for a land-uniformity claim. Sort. If yours is at the top of a list of genuinely similar properties, that is your case.

Look both ways

Find the ones assessed more than you too. The assessor will. If most matched parcels are assessed higher, you do not have a uniformity case and it is far better to learn that at your kitchen table.

This is general information about how Illinois assessments and appeals work. It is not legal advice, not an appraisal, and not a prediction about your case. Deadlines and rules differ by county — check yours with your Board of Review.

Check your own assessment free →

More on Evidence

What makes a comparable good enough to use Similarity on recorded attributes, proximity, and nothing clever. Four tight ones beat twenty loose.Using your county's parcel search like an assessor would Every Illinois county publishes a searchable roll. Most owners never open theirs.Assessed value per square foot: the number that makes comparisons possible Raw assessments cannot be compared. Rates can.Why a Zestimate will not help your appeal Automated values are not accepted as evidence of value, and boards say so out loud.

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