35 ILCS 200/16-65
The board of review shall act as an equalizing authority, if after equalization by the supervisor of assessments the equalized assessed value of property in the county is not 33 1/3% of the total fair cash value. The board shall, after notice and hearing as required by Section 12-40, lower or raise the total assessed value of property in any assessment district within the county so that the property, other than farm and coal property assessed under Sections 10-110 through 10-140 and Sections 10-170 through 10-200, will be assessed at 33 1/3% of its fair cash value. For each assessment district of the county, the board of review shall annually determine the percentage relationship between the valuations at which property other than farm and coal property is listed and the estimated 33 1/3% of the fair cash value of such property. To make this analysis, the board shall use at least 25 property transfers, or a combination of at least 25 property transfers and property appraisals, such information as may be submitted by interested taxing bodies, or any other means as it deems proper and reasonable. If there are not 25 property transfers available, or if these 25 property transfers do not represent a fair sample of the types of properties and their proportional distribution in the assessment district, the board shall select a random sample of properties of a number necessary to provide a combination of at least 25 property transfers and property appraisals as much as possible representative of the entire assessment district, and provide for their appraisal. The township or multi-township assessor shall be notified of and participate in the deliberations and determinations.
In assessment year 2011, the board of review shall consider compulsory sales in its equalization process.
The board of review, in conjunction with the chief county assessment officer, shall determine the number of compulsory sales from the prior year for the purpose of revising and correcting assessments. The board of review shall determine if the number of compulsory sales is at least 25% of all property transfers within the neighborhood, township, multi-township assessment district, or other specific geographic region in the county for that class of property, but shall exclude from the calculation (i) all property transfers for which the property characteristics and condition are not the same as those characteristics and condition used to determine the assessed value and (ii) any property transfer that is not an arm's length transaction based on existing sales ratio study standards (except for compulsory sales). If the board determines that the number of compulsory sales is at least 25% of all property transfers within the defined geographic region for that class of property, then the board of review must determine (i) the median assessment level of arm's length transactions and (ii) the median assessment level of compulsory sales. If the median assessment level of compulsory sales is higher than the median assessment level of arm's length transactions, then compulsory sales shall be included in the arm's length transaction study and the board must calculate the new median assessment level. Assessed values of properties within the specific geographic area for that class of property must be revised to reflect this new median assessment level. The revised median assessment level shall be the basis for equalization as otherwise provided in this Section.
With the ratio determined for each assessment district, the board shall ascertain the amount to be added or deducted from the aggregate assessment on property subject to local assessment jurisdiction, other than farm and coal property, to produce a ratio of assessed value to 33 1/3% of the fair cash value equivalent to 100%. However, in determining the amount to be added to the aggregate assessment on property subject to local jurisdiction in order to produce a ratio of assessed value to 33 1/3% of the fair cash value equivalent to 100%, the board shall not, in any one year, increase or decrease the aggregate assessment of any assessment district by more than 25% of the equalized valuation of the district for the previous year, except that additions, deletions or depletions to the taxable property shall be excluded in computing the 25% limitation. The board shall complete the equalization by the date prescribed in Section 16-35 for the board's adjournment, and, within 10 days thereafter, shall report the results of its work under this Section to the Department. At least 30 days prior to its adjournment, the board shall publish a notice declaring whether it intends to equalize assessments as provided in this Section. The notice shall be published in a newspaper of general circulation in the county. If the board fails to report to the Department within the required time, or if the report discloses that the board has failed to make a proper and adequate equalization of assessments, the Department shall direct, determine, and supervise the assessment so that all assessments of property are relatively just and equal as provided in Section 8-5.
35 ILCS 200/16-65