Where to find recent sales data free
County recorder, assessor sales files, and IDOR declarations — no subscription needed.
You do not need a subscription to find recent sales. Almost everything a board will accept is published, and the paid services largely repackage it.
The sources, best first
1. The county recorder of deeds
Every transfer is recorded. This is the primary source — the actual document, with the actual consideration — and it is what an assessor uses. Most Illinois counties offer an online search by address or PIN.
2. The county assessor's parcel search
Most parcel pages carry a sales history for the property: date, price, and often a deed type or validity code indicating whether the office treated it as arm's length. That last field is worth reading, because it tells you how the county classified the sale.
3. Illinois PTAX-203 declarations
Illinois requires a real estate transfer declaration on most transfers, recording the price and characteristics. These feed the sales data assessors use.
4. Cook County open data
Cook publishes bulk datasets through its open data portal, including parcel sales and assessed values by year. If you are comfortable with a spreadsheet, this is the richest free source available for that county and it is the same data the assessor works from.
5. Multiple listing history, via an agent
An agent can pull closed sales with detail no public source carries — condition, days on market, concessions. Many will do it for a former client without charge.
What makes a sale usable
Not every recorded transfer is evidence of market value. Exclude:
- Transfers between relatives
- Foreclosures and sheriff's sales
- Short sales
- Estate sales
- Transfers into or out of a trust
- Sales that included personal property or a business
- Nominal consideration — a deed reciting $10
These are not arm's length, and a board will discount them. This cuts both ways: if the assessor is using such a sale against you, establishing that it was not arm's length is a real argument.
The date matters
Assessments are made as at a statutory valuation date. Sales close to it carry the most weight. A sale from three years ago in a market that has moved is weak evidence, and a sale from last month may postdate the valuation date entirely.
Presenting them
A table: address, PIN, sale date, price, floor area, price per square foot, and how it compares to your property. State plainly why each is comparable, and note any adjustment you have made and why.
The alternative that needs no sales at all
If sales data is thin in your area — common in stable neighbourhoods where nothing changes hands — a uniformity argument needs none of it. You are comparing assessments against assessments, all of which the county has already published. It is frequently the easier path, and it is available in exactly the situations where market evidence is hardest to find.