Will County has received a final property assessment equalization factor of 1.0000 for 2025, according to David Harris, director of the Illinois Department of Revenue (IDOR). The equalization factor, also known as the “multiplier,” is used to ensure that property assessments are uniform across counties in Illinois. This process is important because many of the state’s local taxing districts overlap multiple counties.
Illinois law requires that most property be assessed at one-third of its market value. Farm properties are assessed differently, with farm homesites and dwellings following regular procedures, while farmland is valued at one-third of its agricultural economic value and is not subject to the state equalization factor.
Assessments in Will County are currently at 33.46% of market value, based on sales from 2022 through 2024. The new equalization factor applies to taxes payable in 2026. Last year’s factor was also set at 1.0000.
The final multiplier was issued after a public hearing on the tentative factor, which was also set at 1.0000 on October 23, 2025. The IDOR determines this factor annually by comparing property sale prices over three years with their assessed values.
If the average level of assessment matches one-third of market value, the multiplier is set at one. If assessments are higher than one-third, the multiplier drops below one; if lower, it rises above one.
A change in the equalization factor does not directly affect total property tax bills. Local taxing bodies determine tax bills based on their funding requests each year. If these requests do not exceed those from previous years, overall taxes will not increase even if assessments rise.
The assessed value of an individual property establishes what share of taxes a taxpayer pays but does not change due to the multiplier.
The Illinois Department of Revenue oversees state tax collection and provides financial information to residents and businesses throughout Illinois (official website). The agency emphasizes fair administration of tax laws and efficient revenue collection (official website). It also works to foster diversity and equity for both employees and customers (official site).
