An applicant for a CDL must be a minimum of: Do you currently have car insurance? Insurance is mandatory to drive in Ohio Yes I have insurance. But please show me your best quotes. No, please help me find the best insurance. Question An applicant for a CDL must be a minimum of: Answers 18 years old. 21 years old. 25 years old. Explanation In Vermont, you must be at least 18 years old to obtain a CDL. To be licensed to operate in interstate commerce, you must be at least 21 years old. This questions appears in the following tests: Vermont Class A Knowledge Test