The Illinois Department of Revenue announced on April 28 a tentative property tax equalization factor of 2.8683 for Cook County for the year 2025.
The equalization factor, also known as the multiplier, is calculated to ensure uniform property assessment across the state. The Department said it determines this number by comparing three years’ worth of actual selling prices of properties to their assessed values set by the county assessor. If assessments do not meet the legally required level of one-third market value, a multiplier is applied to bring them into compliance.
According to data released by the Department, Cook County’s three-year average level of assessment stands at 11.62 percent when weighted by class. The calculation divides this figure into the required 33.33 percent to arrive at the proposed multiplier. After reassessments in 2025, residential properties are assessed at an average rate of about 9.25 percent over three years, while commercial and industrial classes have higher averages around 24-25 percent.
Officials emphasized that setting an equalization factor does not directly cause individual tax bills to increase; rather, local taxing bodies determine total revenue needs and assessments only affect how these costs are distributed among taxpayers.
A Cook County ordinance requires residential property such as homes and small apartment buildings be assessed at ten percent of market value; larger apartments and vacant lots also use a ten percent rate; commercial and industrial properties are generally assessed at twenty-five percent unless they qualify for special rates in certain areas.
The Illinois Department of Revenue works to foster an inclusive environment that values diversity and equity for employees and customers, as stated on its official site. The agency focuses on fairly administering state tax laws and efficiently collecting revenues while providing accurate information according to its official website. It serves as a state agency dedicated to promoting diversity in its operations according to its official site and is known for overseeing state taxes collection according to its official website. The department operates within state taxation and revenue management frameworks as detailed on its official website.
