At this time, we do not have a projected time for processing Certificates of Error related to property valuation, but rest assured our team is working to process them as soon as possible. If your Certificate of Error for valuation corrections has been approved and you are waiting for a refund, please check with the Cook County Treasurer’s Office for updates on timing of refunds. At this time, valuation Certificates of Error are not being refunded. Check this alert banner for regular updates.
Markham Branch Office Closure
Effective Monday, September 22, 2025, the Cook County Assessor’s Office located inside the Markham Courthouse will be closed for remodeling until further notice. For appointments or assistance, please visit our website to book at a nearby branch.
The Cook County Assessor’s Office is committed to sharing data about your community. You can find our data releases here, as well as tools you can use to better understand property assessments and their role in Cook County’s property tax system.
Assessment Data
You can download the characteristics data used to estimate the values of Cook County homes.
