Even though most Evanstonians may have received lowered assessments on their residences, none can be assured of a lower property tax bill.

Property tax assessments, mailed to residents last month, are on average about 12 percent lower than the last assessment, said Cook County Commissioner Larry Suffredin at a town hall meeting on July 22. “The median drop in this area is 12 percent,” he said, adding that the Assessor’s office said that the assessed valuation is supposed to be about 10 percent of the fair market value.

“This process is to guarantee that you’re paying only your fair share of taxes,” Mr. Suffredin said. The assessed valuation ranks a residence in comparison to other homes in the area.

The assessed valuation is used to determine a property owner’s proportionate share of the taxes levied by each taxing body. About 15 taxing bodies take a bite from the Cook County property tax bill. School Districts 65 and 202 together receive about 67 percent of the revenues, and the City of Evanston receives about 20 percent.

Each taxing body determines its own annual tax levy, and the assessment is used to determine each property owner’s proportionate share of that tax burden for that taxing body. Thus if a taxing body such as the City of Evanston levies a higher amount of property taxes, property owners collectively have to pay the higher taxes even if the assessed value of all property in Evanston declined by 12 percent – as is likely to be the case in the upcoming fiscal year’s budget. What generally changes after an assessment is each individual property owner’s share of those taxes.

Each year the Cook County Assessor – currently James Houlihan – assesses one-third of the properties in Cook County, so that each property is assessed every three years. About 13,000 homes and 9,000 condos were assessed with a valuation as of Jan. 1 of this year, said Mr. Suffredin. He said he encourages everyone who believes their assessment is too high to contact his office. The deadline for appealing property tax assessments is Aug. 16.