About

The Assessor's Office is responsible for setting fair and accurate values for 1.8 million parcels of Cook County property. The value of these properties is not determined on an individual basis, but rather by a mass appraisal system. The mass appraisal system is a way to put fairness into the entire assessment process.

Responsibilities of the Assessor's Office

Our public service responsibilities, however, are not limited to setting property values. In addition to working with other government agencies to stimulate economic development, job creation and the construction of affordable housing, we also seek to help county residents better understand the assessment process and take advantage of money-saving exemptions the office provides.

The Assessor's Office has also taken the lead on developing both short-term property tax relief proposals as well as working toward the overall restructuring of the tax system to make it more equitable for all taxpayers.

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 1.8 million parcels of property is conducted for ad valorem tax purposes. Ad valorem means according to value and refers to the amount of taxes that will be required to be paid based on the value of the property.

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.

The Assessor’s public service responsibilities, however, are not limited to setting property values. In addition to working with other government agencies to stimulate economic development, job creation and the construction of affordable housing, the Assessor also seeks to help county residents better understand the assessment process and take advantage of money-saving exemptions the office provides.

The Assessor's Role In the Tax Cycle

The Cook County Assessor places a value on close to 1.8 million parcels in Cook County.

Triennial Reassessments

Reassessment of property in Cook County is done within a triennial cycle, meaning it occurs every three years. The Cook County Assessor's Office alternates reassessments between the north and west suburbs, the south and west suburbs and the City of Chicago.

Triennial Reassessment Cycle & Map

Triennial Reassessment Cycle & Map

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Reassessment Years 2015 and 2018
Townships
Hyde Park Jefferson Lake Lakeview
North Rogers Park South West
Reassessment Years 2013 and 2016
Townships
Barrington Elk Grove Evanston Hanover
Leyden Maine NewTrier Niles
Northfield Norwood Park Palatine Schaumburg
Wheeling      
Reassessment Years 2014 and 2017
Townships
Berwyn Lyons River Forest Bloom
Oak Park Riverside Bremen Orland
Stickney Calumet Palos Thornton
Cicero Proviso Worth Lemont
Rich      

Valuation through Multiple Regression

To determine the property value of a single family home, the Assessor's Office uses a technique called multiple regression. This technique creates a type of sales comparison average, a mathematical relationship between the value of your house and those of your neighbors. It follows similar steps that an appraiser would take when valuing a single family home. The key concern in residential property assessment is uniformity. The rule of uniformity requires that property be valued with property of like kind. The sales comparison average ensures that similar properties are assessed similarly.

Mapping the Townships

An integral part of the reassessment process is the collection of data regarding economic and neighborhood trends. The data is then used to define neighborhoods which have similar housing types and sale prices. The defined neighborhoods are then mapped and assigned neighborhood codes, a necessary component of the multiple regression process.

In suburban townships or Chicago neighborhoods which will undergo triennial reassessments, the Assessor's staff meets with local elected officials, community leaders, real estate professionals and other citizens knowledgeable about real estate in the area. This helps to verify or correct assessment neighborhood boundaries before they are finalized.

The Appeals Process

With nearly 1.8 million parcels of property in Cook County, mistakes may occur during the reassessment process. The Assessor’s Office encourages taxpayers to review their proposed assessments and file appeals if necessary. The assessor has a friendly and informative staff available to help taxpayers file appeals.

Tax Savings through Exemptions

Property owners should be aware that there is tax relief available through property tax exemptions.