It is usually 6 months. Check your permit after you receive it. It has the expiration date on it. Always remember that your CDL permit must be valid at the final exam time after your complete school. School takes around 3-4 weeks to complete. TruckTrailerPro CDL School takes you to the final exam right away after you graduate, but it can vary at other schools depending on how busy their test sites are. Some states have very long waiting times. Always ask that question to your CDL school before you register with them.