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2021 Cook County Equalization Factor Finalized

The Illinois Department of Revenue (IDOR) finalized the 2021 Cook County Equalization Factor of 3.0027 on Tuesday, October 18, 2022.  Since Cook County is the only County in the State of Illinois that “classifies” and thereby “assesses” different types of properties based on their use, the IDOR is required to configure and implement an annual equalization factor or “multiplier” to bring Cook County’s average level of assessments to the required state-wide 33-1/3 percent level of assessment.  The IDOR determines the equalization factor for each County by comparing, the actual selling price of individual properties within the County over a three-year period, to the assessed values that were given to those properties by the County Assessor.    If the median level of assessment for all property in the county varies from the 33-1/3 percent assessment level required by law, the equalization factor is utilized to bring all of the assessments within the County to the legally mandated level.  

For the most recent three-year period (2018-2020), the average level of assessments for Cook County is 11.10 percent as weighted by class.  The IDOR divides Cook County’s three-year average of 11.10 into 33.33 to calculate the multiplier and bring the average level of assessments to the required 33-1/3 percent level.  

The 2021 final equalization factor of 3.0027 is a 10.00% increase from the 2021 tentative equalization factor of 2.7297 that was released by IDOR in June, 2022.  

The next step before the second installment 2021 tax bills issue is for the Cook County Clerk to set the local 2021 tax rates which are determined based on taxing district’s budgets which quantify the dollars needed to fund the variety of services provided to the citizens for things like education, police and fire protection, libraries, park districts and more.  

Public reports have forecasted that the second installment 2021 tax bills will issue in November, 2022 with payments due no less than 30 days after the issuance of the second installment tax bills.