625 ILCS 5/13-103.1

Only certified safety testers are authorized to perform safety tests and affix Certificates of Safety to vehicles. The Department shall annually certify those certified safety testers and certified diesel emission testers who have met its requirements. Certified safety testers' and certified diesel emission testers' certificates shall expire 12 months following the date of issue, but may be renewed annually by complying with the requirements as established by the Department.