To be honest, I’ve read and re-read this article about four times — and I’m still not sure I entirely understand how property tax assessment works. Here are the highlights, for those of you who want to know more. Click the link at the bottom for access to the chart showing assessment levels by class. And for anyone who really “gets” the process, please feel free to share with us in the comments section.

The Illinois Department of Revenue announces the final 2018 equalization factor of 2.9109 for Cook County. The department is required by law to calculate the factor, also called the multiplier, to achieve uniform property assessment throughout the state.

The department determines the final equalization factor for each county by comparing the actual selling price of individual properties, over a three-year period, with the assessed value placed on those properties by the county assessor and adjusted by the board of review. If the median level of assessment for all property in the county varies from the 33 1/3 percent level required by law, an equalization factor is assigned to bring assessments to the legally mandated level.

A Cook County ordinance requires that residential property (homes, condominiums, apartment buildings of six units or less) be assessed at 10 percent of market value; all other residential property (apartments with more than six units), 10 percent; vacant lots, 10 percent; property owned by not-for-profit corporations, 25 percent; commercial property, 25 percent; industrial property, 25 percent; and commercial or industrial property being developed in economically deprived areas, usually 10 percent.

Source: 2018 Cook County Final Multiplier Announced – Press Releases & News Archive