If you plan to haul hazardous materials in a tank, one endorsement is not enough. You need both the tank vehicle endorsement and the hazmat endorsement, and states combine those into a single code: the X endorsement. Knowing what it bundles together saves confusion when you apply.
This is study guidance, not regulatory advice. The endorsement framework is in 49 CFR 383.93 and your official state CDL manual.
What the X endorsement is
The X endorsement is shorthand for holding both the tank vehicle (N) and hazmat (H) endorsements at once. Rather than list two separate codes, the license shows X to indicate the driver is authorized for hazardous materials in tank vehicles.
| Endorsement | Covers |
|---|---|
| N (tank vehicle) | Driving tank vehicles |
| H (hazmat) | Hauling placarded hazardous materials |
| X | Both N and H combined |
What it takes to earn it
Because X combines two endorsements, you have to satisfy both. That means passing the tank vehicle knowledge test, passing the hazmat knowledge test, and clearing the TSA Security Threat Assessment that the hazmat side requires. The hazmat portion is the same material covered in what to expect on the CDL hazmat test, and the background check is the same one behind the hazmat endorsement requirements.
Why combine them
Tank loads of hazardous materials carry the combined risks of both: a large, shifting liquid load and a hazardous substance. Requiring both endorsements ensures the driver understands tank handling and hazmat rules together. It also explains why the TSA check applies, the same one discussed in TWIC versus the hazmat endorsement.
Where it fits
Earning the X is part of preparing thoroughly, which is the goal of how to pass the CDL hazmat test on your first try. For the federal framework, see the FMCSA hazardous materials regulations and the endorsement rules in 49 CFR 383.93.
Frequently asked questions
What is the X endorsement on a CDL?
It is a combined endorsement covering both the tank vehicle (N) and hazmat (H) endorsements. It authorizes a driver to haul hazardous materials in tank vehicles.
How do you get the X endorsement?
Pass both the tank vehicle and hazmat knowledge tests and clear the TSA Security Threat Assessment required for the hazmat side. The license then shows X for the combined authorization.
Do you need the X endorsement to haul fuel in a tanker?
If the load is a placarded hazardous material in a tank, you need both the tank and hazmat endorsements, which is what the X represents. Check your specific load and your state rules.
What is the best way to study for the X endorsement?
Study the tank and hazmat sections of your state manual, and drill placard recognition for the hazmat side with an app such as CDL Placards. Your state CDL manual is the authority on the tests.
