The Role of the Cook County Assessor

The Cook County Assessor is an elected government official who is responsible for establishing fair and accurate property assessments. Valuation of the county’s 1.7 million parcels of property is conducted for ad valorem tax purposes.  Ad valorem means according to real estate value and refers to the amount of tax a property is required to pay according to its value.

To administer this task, the Assessor reassesses one-third of the properties located in the county each year. The Assessor alternates assessments among the northern suburbs, the southern suburbs and the City of Chicago.   For example, a property reassessed in 2007 will be reassessed next in the year 2010.

How We Value Residential Property

The Cook County’s Assessor’s Office is responsible for valuing the more than 1.1 million residential parcels in Cook County. Cook County is divided into three assessment districts (City, North and South). Each of the assessment districts is valued once every three years.  

The Cook County Assessor’s Office uses a computer-assisted mass appraisal method to value residential properties. This computerized sales comparison model considers several different value components including, but not limited to,  sales of comparable properties, land, location, building square footage, and construction type. These are some of the very same factors that would be considered by an appraiser seeking to value a property.  View all details

How We Value Commercial / Industrial

Valuation techniques have been developed for the different types of properties in Cook County. Physical features of buildings often indicate value. For example, apartments may be valued by number of units and unit mix while industrial properties are valued by amenities such as number of loading docks and the building size. For these reasons, the Cook County Assessor collects information on all of the properties we assess.   View all details