65 ILCS 5/8-12-4
In order to receive assistance as provided in this Division, a home rule municipality shall first, by ordinance passed by its corporate authorities, request (i) that the Department of Revenue certify that it is in the highest 5% of all home rule municipalities in terms of the aggregate of the rate per cent of all taxes levied pursuant to statute or ordinance upon all taxable property of the municipality and in the lowest 5% of all home rule municipalities in terms of per capita tax yield, and (ii) that the General Assembly by joint resolution designate it as a financially distressed city. A home rule municipality which is so certified and designated as a financially distressed city and which desires to receive assistance as provided in this Division shall, by ordinance passed by its corporate authorities, request that a financial advisory authority be appointed for the city and that the city receive assistance as provided in this Division, and shall file a certified copy of that ordinance with the Governor, with the Clerk of the House of Representatives and with the Secretary of the Senate. Upon the filing of the certified copies of that ordinance as required by this Section this Division and all of its provisions shall then and thereafter be applicable to the financially distressed city, shall govern and control its financial accounting, budgeting and taxing procedures and practices, and, subject to the limitations of subsection (a) of Section 8-12-22, shall remain in full force and effect with respect thereto until such time as the financial advisory authority established under Section 8-12-5 is abolished as provided in subsection (c) of Section 8-12-22.
65 ILCS 5/8-12-4