820 ILCS 112/20
An employer subject to any provision of this Act shall make and preserve records that document the name, address, and occupation of each employee, the wages paid to each employee, the pay scale and benefits for each position, the job posting for each position, and any other information the Director may by rule deem necessary and appropriate for enforcement of this Act. An employer subject to any provision of this Act shall preserve those records for a period of not less than 5 years and shall make reports from the records as prescribed by rule or order of the Director, unless the records relate to an ongoing investigation or enforcement action under this Act, in which case the records must be maintained until their destruction is authorized by the Department or by court order.
820 ILCS 112/20