The Cook County Assessor's Office determines the assessed value of property in Cook County. It does not calculate or send out tax bills.
However, in accord with its mission to inform the public about how property taxes in Cook County work, the CCAO does conduct research into different parts of the property tax system.
The below data dashboard explores the number of homeowners in Cook County that experienced property tax bill spikes between Tax Year 2021 and Tax Year 2023.
What constitutes a property tax spike? The default setting for the data dashboard defines a tax spike as a tax bill increase of at least 25% and $500 over the previous year. But the dashboard allows users to change these parameters, as well as explore the number of homeowners with bill spikes by municipality, township, legislative districts, and Chicago wards.