225 ILCS 130/30

In addition to any other information required to be contained in the application, every application for an original certificate of registration under this Act shall include the applicant's Social Security Number or individual taxpayer identification number, which shall be retained in the agency's records pertaining to the registration. As soon as practical, the Department shall assign a customer's identification number to each applicant for a registration. Every application for a renewed, reinstated, or restored registration shall require the applicant's customer identification number.