There are six endorsements, and they are single letters on your license. A lot of study material blurs them together with the core knowledge tests, which leaves drivers paying for material they do not need or missing one they do.
The six endorsements
- H, Hazardous Materials. Required to transport any quantity of hazardous materials that require placarding under federal hazmat regulations. This one also needs a TSA background check and fingerprinting, so start it early: it is the longest lead time of anything here.
- N, Tank Vehicles. Required for vehicles designed to transport liquids or gases in a tank attached to the vehicle, permanently or temporarily, above the regulated capacity.
- P, Passenger. Required for commercial vehicles designed to carry 16 or more passengers including the driver: charter buses, transit coaches and similar.
- S, School Bus. Required for any driver transporting school-age students in a vehicle classified as a school bus under federal or state law. S sits on top of P rather than replacing it.
- T, Doubles and Triples. Required to pull double or triple trailers where state law permits them.
- X, Hazmat and Tank combined. Not a seventh subject. X is what you hold when you carry both H and N, which is the normal case for hauling placarded liquid loads.
Two things that are not endorsements
This is where most of the confusion lives.
Air Brakes is a restriction removal, not an endorsement. If you do not pass it, your license is issued with a restriction barring you from air-braked vehicles. Nothing is added to your license when you pass. The restriction is simply absent. That covers most Class A tractor-trailers and many Class B straight trucks, so it is rarely optional in practice.
Combination Vehicles is a core knowledge test. It is part of qualifying for Class A, not an add-on. General Knowledge is the same: everyone takes it.
So a Class A driver hauling placarded fuel is not taking "four endorsements". They are taking General Knowledge and Combination Vehicles as core tests, clearing the air brake restriction, and adding H and N, which shows as X.
Pick the ones your job actually needs
Endorsements are not a collection to complete. Each is a separate knowledge test, and an unused one earns you nothing. Work from the vehicle and the cargo backwards.
- See the endorsements for your state, with what each one requires.
- Use the CDL Selector if you are unsure which apply to the work you are taking.
You can buy a single endorsement test on its own, or a class bundle if you need several. Pay once, no subscription.