(35 ILCS 200/4-20)
    Sec. 4-20. Additional compensation based on performance. Any assessor in counties with less than 3,000,000 but more than 50,000 inhabitants each year may petition the Department to receive additional compensation based on performance. To receive additional compensation, the official's assessment jurisdiction must meet the following criteria:
        (1) the median level of assessment must be no more
    
than 35 1/3% and no less than 31 1/3% of fair cash value of property in his or her assessment jurisdiction; and
        (2) the coefficient of dispersion must not be greater
    
than 15%.
For purposes of this Section, "coefficient of dispersion" means the average deviation of all assessments from the median level. For purposes of this Section, the number of inhabitants shall be determined by the latest federal decennial census. When the most recent census shows an increase in inhabitants to over 50,000 or a decrease to 50,000 or fewer, then the assessment year used to compute the coefficient of dispersion and the most recent year of the 3-year average level of assessments is the year that determines qualification for additional compensation. The Department will promulgate rules and regulations to determine whether an assessor meets these criteria.
    Any assessor in a county of 50,000 or fewer inhabitants may petition the Department for consideration to receive additional compensation each year based on performance. In order to receive the additional compensation, the assessments in the official's assessment jurisdiction must meet the following criteria: (i) the median level of assessments must be no more than 35 1/3% and no less than 31 1/3% of fair cash value of property in his or her assessment jurisdiction; and (ii) the coefficient of dispersion must not be greater than 40% in 1994, 38% in 1995, 36% in 1996, 34% in 1997, 32% in 1998, and 30% in 1999 and every year thereafter.
    Real estate transfer declarations used by the Department in annual sales-assessment ratio studies will be used to evaluate applications for additional compensation. The Department will audit other property to determine if the sales-assessment ratio study data is representative of the assessment jurisdiction. If the ratio study is found not representative, appraisals and other information may be utilized. If the ratio study is representative, upon certification by the Department, the assessor shall receive additional compensation of $3,000 for that year, to be paid out of funds appropriated to the Department from the Personal Property Tax Replacement Fund.
    As used in this Section, "assessor" means any township or multi-township assessor, or supervisor of assessments.
(Source: P.A. 97-72, eff. 7-1-11.)