To obtain a CDL, you must be at least: Before you start the test, please answer the question below regarding your insurance status. Without insurance you will not be able to drive in Ohio Do you currently have car insurance? Yes I have insurance. Great, you're all set! Click here if you still want to compare rates. No, I need insurance. Click here to compare rates from our insurance partner. Question To obtain a CDL, you must be at least: Answers 15 years old. 18 years old. 21 years old. 25 years old. Explanation In Pennsylvania, you must be at least 18 years old to obtain a CDL. To operate a commercial vehicle in interstate commerce, you must be at least 21. This questions appears in the following tests: Pennsylvania Class B Knowledge Test