X Endorsement CDL: Tanker + Hazmat Explained

N, H and X side by side

Code	What it covers	Knowledge test	TSA security check	Skills test
N	Tank vehicle	Tank vehicle	No	None for the endorsement
H	Hazardous materials	Hazardous materials	Yes	None for the endorsement
X	Tank vehicle and hazardous materials	Both	Yes	None for the endorsement

"None for the endorsement" means 49 CFR 383.93 lists a knowledge test only for these endorsements. You still take the CDL skills test for your class. Your state may add steps, so ask your licensing office.

Which tests you take for X

You take two knowledge tests:

The tank vehicle test. It is built on Section 8 of the CDL manual.

The hazardous materials test. It is built on Section 9.

The hazmat half has its own question count in each state: hazmat counts by state. If it is your first hazmat endorsement, the H part brings ELDT theory training before the test.

The manual also tells tanker drivers to study Sections 2, 5, 6 and 9. Section 2 is general driving. Section 5 is air brakes. Section 6 is combination vehicles.

Not sure where to start? The free tanker endorsement practice test and hazmat practice test use exam-style questions built from the official CDL manual. Here is a 10-question tanker set:

Why the TSA check applies

X includes hazmat, so you need the TSA security threat assessment. 49 CFR 383.141 says a state may not issue, renew, upgrade or transfer a hazmat endorsement unless TSA has decided you are not a security risk, or you hold a valid TWIC.

The manual says the check reviews criminal, immigration and FBI records. You also submit fingerprints. If TSA finds you are a threat, the state denies the endorsement.

Federal rules say a state must require hazmat endorsements to be renewed every 5 years or less, so you face the TSA check at least that often. The steps for enrolling vary, so your licensing office is the place to start.

What the tanker test covers

Each point below comes from the Section 8 text in the manual.

Leaks come first. Section 8.1.1 says the most important item to check on a tank vehicle is leaks. Carrying liquids or gases in a leaking tank is a crime.
Valves and covers. Section 8.1.2 says never to drive with open valves or manhole covers.
Rollovers. Section 8.2.1 says tankers can turn over at the posted speed for a curve. Take curves well below it.
Surge. Section 8.2.2 says liquid moving in a partly filled tank can push the truck.
Baffles and smooth bore tanks. Sections 8.2.4 and 8.2.5 cover them. Baffles slow forward and back surge. Side-to-side surge can still roll you. A smooth bore tank has nothing inside to slow the liquid.
Outage. Section 8.2.6 says never load a tank totally full, because liquids expand as they warm.
Driving rules. Section 8.3 covers smooth driving, controlling surge, curves, stopping distance and skids.

Federal rules back this up. 49 CFR 383.119 lists surge, braking when empty, full and partly full, baffled and non-baffled tanks, and road grade and curves.

For the full breakdown, read the tanker endorsement test guide.

What the hazmat test covers

Section 9.1.3 says that to pass, you must know how to identify hazardous materials, safely load shipments, properly placard your vehicle, and safely transport shipments.

Placards. Section 9.3.10 says to attach placards before you drive. They go on both sides and both ends of the vehicle.
Shipping papers. Section 9.3.5 says the basic description includes the identification number, proper shipping name, hazard class or division, and packing group.
Tank loading. Section 9.5.2 says someone qualified must watch a cargo tank during loading and unloading. That person must be alert, have a clear view of the tank, and stay within 25 feet of it.
Railroad crossings. Section 9.6.12 says to stop 15 to 50 feet before the nearest rail if you are placarded or have cargo tanks used for hazardous materials.
Emergencies. Section 9.7.1 explains the Emergency Response Guidebook. It is indexed by proper shipping name and identification number.

Federal rules list the hazmat topics in 49 CFR 383.121. They include the hazardous materials table, shipping papers, marking, labeling, placarding, loading, parking, routes and cargo tanks.

For more, read the hazmat endorsement test guide. To see how every endorsement fits together, see all CDL endorsement tests.

Where to start

Study tanker first if you drive a tank now. Study hazmat first if you haul placarded loads now. Start your TSA enrollment early.

If you will haul tanker or hazmat freight under your own authority, the MC number guide covers getting your authority set up.

Common questions

What is the X endorsement on a CDL?

X is the code for a combination of the tank vehicle and hazardous materials endorsements. Federal rules list it in 49 CFR 383.153. It shows you passed both knowledge tests.

Do I need the TSA background check for the X endorsement?

Yes. X includes the hazmat endorsement, so you need the TSA security threat assessment. 49 CFR 383.141 says a state may not issue, renew, upgrade or transfer a hazmat endorsement until TSA finds you are not a security risk, or you hold a valid TWIC. Your state licensing office will tell you how to enroll.

Is there a skills test for the X endorsement?

Federal rules list a knowledge test only for the tank vehicle and hazardous materials endorsements. You still take the regular CDL skills test for your vehicle class. Your state may add steps, so ask your licensing office.