35 ILCS 200/9-45
The county clerk in counties of 3,000,000 or more inhabitants and, subject to the approval of the county board, the chief county assessment officer or recorder, in counties of less than 3,000,000 inhabitants, may establish a property index number system under which property may be listed for purposes of assessment, collection of taxes or automation of the office of the recorder. The system may be adopted in addition to, or instead of, the method of listing by legal description as provided in Section 9-40. The system shall describe property by township, section, block, and parcel or lot, and may cross-reference the street or post office address, if any, and street code number, if any. The county clerk, county treasurer, chief county assessment officer or recorder may establish and maintain cross indexes of numbers assigned under the system with the complete legal description of the properties to which the numbers relate. Index numbers shall be assigned by the county clerk in counties of 3,000,000 or more inhabitants, and, at the direction of the county board in counties with less than 3,000,000 inhabitants, shall be assigned by the chief county assessment officer or recorder. Tax maps of the county clerk, county treasurer or chief county assessment officer shall carry those numbers. The indexes shall be open to public inspection and be made available to the public. Any property index number system established prior to the effective date of this Code shall remain valid. However, in counties with less than 3,000,000 inhabitants, the system may be transferred to another authority upon the approval of the county board.
Any real property used for a power generating or automotive manufacturing facility located within a county of less than 1,000,000 inhabitants, as to which litigation with respect to its assessed valuation is pending or was pending as of January 1, 1993, may be the subject of a real property tax assessment settlement agreement among the taxpayer and taxing districts in which it is situated. In addition, any real property that is located in a county with fewer than 1,000,000 inhabitants and (i) is used for natural gas extraction and fractionation or olefin and polymer manufacturing or (ii) is used for a petroleum refinery may be the subject of a real property tax assessment settlement agreement among the taxpayer and taxing districts in which the property is situated if litigation is or was pending as to its assessed valuation as of January 1, 2003 or thereafter. Other appropriate authorities, which may include county and State boards or officials, may also be parties to such agreements. Such agreements may include the assessment of the facility or property for any years in dispute as well as for up to 10 years in the future. Such agreements may provide for the settlement of issues relating to the assessed value of the facility and may provide for related payments, refunds, claims, credits against taxes and liabilities in respect to past and future taxes of taxing districts, including any fund created under Section 20-35 of this Act, all implementing the settlement agreement. Any such agreement may provide that parties thereto agree not to challenge assessments as provided in the agreement. An agreement entered into on or after January 1, 1993 may provide for the classification of property that is the subject of the agreement as real or personal during the term of the agreement and thereafter. It may also provide that taxing districts agree to reimburse the taxpayer for amounts paid by the taxpayer in respect to taxes for the real property which is the subject of the agreement to the extent levied by those respective districts, over and above amounts which would be due if the facility were to be assessed as provided in the agreement. Such reimbursement may be provided in the agreement to be made by credit against taxes of the taxpayer. No credits shall be applied against taxes levied with respect to debt service or lease payments of a taxing district. No referendum approval or appropriation shall be required for such an agreement or such credits and any such obligation shall not constitute indebtedness of the taxing district for purposes of any statutory limitation. The county collector shall treat credited amounts as if they had been received by the collector as taxes paid by the taxpayer and as if remitted to the district. A county treasurer who is a party to such an agreement may agree to hold amounts paid in escrow as provided in the agreement for possible use for paying taxes until conditions of the agreement are met and then to apply these amounts as provided in the agreement. No such settlement agreement shall be effective unless it shall have been approved by the court in which such litigation is pending. Any such agreement which has been entered into prior to adoption of this amendatory Act of 1988 and which is contingent upon enactment of authorizing legislation shall be binding and enforceable.
35 ILCS 200/9-45