How do I find my Property Index Number (PIN) to appeal my Cook County assessment?
How do I find my Property Index Number (PIN) to appeal my Cook County assessment?
Your 14-digit Property Index Number (PIN) is the ID Cook County uses for your parcel — find it on your tax bill, deed, or assessment notice, or look it up by address on the Assessor's website, and you'll need it to file any appeal.
The Property Index Number (PIN) is the 14-digit identifier Cook County assigns to your parcel. Every assessment appeal — to the Assessor, the Board of Review, or the state Property Tax Appeal Board — is keyed to your PIN, so you need it before you can file.
Where to find it. Your PIN is printed on:
- your property tax bill from the Cook County Treasurer,
- your closing documents and deed, and
- notices from the Assessor's office, including your reassessment notice.
See the Assessor's guide, Where do I find my PIN?.
Look it up by address. If you cannot locate a document, use the Assessor's Search by Address tool. Enter your address to retrieve your PIN along with your estimated market value, assessed value, and property characteristics. You can also reach the same data through the Assessor's property details tool, which shows permits, divisions and consolidations, and exemption history.
Use the PIN to build your appeal. Once you have your PIN you can:
- Confirm the assessed value the Assessor assigned (multiply by 10 for the implied fair market value under the 10% residential level).
- Check the property characteristics on record — square footage, room count, building class — for errors you can challenge.
- Pull Neighborhood Sales for comparable transactions within the last 36 months, useful evidence that your home is over-assessed.
If your property has multiple PINs (for example, a parcel that was divided or a condo with separately numbered units), confirm which PIN matches the assessment you are appealing — filing under the wrong PIN can invalidate your appeal.