CDL Endorsements Explained: H, N, P, S, T, X

CDL endorsements expand what you're legally allowed to haul or drive. Each endorsement requires passing an additional written test. Some also require a skills test or background check.

H — Hazardous Materials (HazMat)

Required to transport hazardous materials in quantities that require placards. This endorsement requires a TSA background check in addition to the written test. The test covers hazmat classification, loading procedures, placarding, and emergency response.

N — Tanker

Required to drive tank vehicles that transport liquids or gases in bulk. The test focuses on the unique handling characteristics of liquid cargo — surge, high center of gravity, and the effects of partial loads on vehicle stability.

P — Passenger

Required to drive vehicles designed for 16 or more passengers (including the driver). Covers passenger safety, loading/unloading, emergency exits, and handling unruly passengers. A skills test in a passenger vehicle is also required.

S — School Bus

Required to drive a school bus. Requires both a written test and a skills test in a school bus. Covers student loading zones, school bus-specific traffic laws, railroad crossing procedures, and emergency evacuations.

T — Doubles/Triples

Required to pull double or triple trailers. The test covers coupling/uncoupling procedures, inspection of multiple trailers, and the driving challenges specific to longer combination vehicles.

X — Combination (HazMat + Tanker)

The X endorsement combines H and N. Rather than taking two separate tests, you can take one combined test. You still need the TSA background check. This endorsement is required to transport hazardous materials in a tank vehicle.