225 ILCS 120/27

In addition to any other information required to be contained in the application, every application for an original license under this Act shall include the applicant's social security number, individual taxpayer identification number, or other unique identifying number deemed appropriate by the Department, which shall be retained in the agency's records pertaining to the license. As soon as practical, the Department shall assign a customer's identification number to each applicant for a license. Every application for a renewal or restored license shall require the applicant's customer identification number.