Question To obtain a CDL, an applicant must be at least: Answers 15 years old. 18 years old. 21 years old. 25 years old. Explanation You must be at least 18 years old to obtain a CDL. However, you must be 21 years old to drive in interstate commerce or to obtain a passenger or hazardous materials endorsement. Take a FREE Practice Test Now This questions appears in the following tests: New Jersey Knowledge Test Class B ,