CDL Endorsement Tests: Every Letter and Its Test

A CDL endorsement is a letter on your license that lets you drive a special kind of vehicle or haul special cargo. Every endorsement has a written knowledge test, and passenger and school bus also have a skills test (49 CFR 383.93).

Federal rules list six endorsement letters (49 CFR 383.153). Five of them cover a type of vehicle or cargo, and X combines two of them.

The CDL endorsement letters and their tests

Letter	What it lets you drive	Knowledge test	Also required
H Hazmat	Vehicles hauling hazardous materials that need placards	Hazmat test (study guide, how hard is it)	TSA security threat assessment with fingerprints
N Tank vehicle	Tank vehicles over the manual's size rule (see below)	Tanker test (study guide)	None listed in 49 CFR 383.93
P Passenger	Vehicles designed to carry 16 or more people, including the driver	Passenger test (study guide)	Skills test in a passenger vehicle
S School bus	School buses	School Bus test (study guide)	Skills test in a school bus, and you must also qualify for P
T Doubles/triples	Double or triple trailers	Doubles/Triples test (study guide)	None listed in 49 CFR 383.93
X Tank and hazmat	Tank vehicles hauling placarded hazmat	Tanker test and Hazmat test	X is N and H together, so what H needs (the TSA check) comes with it

Watch the letters. T is doubles and triples, and N is tank vehicle. They don't match the first letter of every name.

Your state may add its own endorsements. The manual says states can do that.

What the table means in plain words

H, hazmat. The manual says you need H to haul material that is hazardous under federal law and must be placarded. Before a state can issue it, TSA must decide you do not pose a security risk that warrants denial (49 CFR 383.141). The manual says the background check includes fingerprints. This check is a government step. FirstTry CDL only helps with the written test.

N, tank vehicle. The manual says you need it for a tank or tanks with an individual rated capacity of more than 119 gallons and an aggregate rated capacity of 1,000 gallons or more, attached to the vehicle or chassis. The liquid does not have to be hazardous. The manual says it applies to Class A and B, and to Class C only when the vehicle hauls hazmat. You can try the tanker endorsement test questions with a reason for each answer.

P, passenger. The manual says you need it for a vehicle designed to carry 16 or more people, including the driver. It applies to a bus in any class.

S, school bus. The school bus test comes on top of the passenger endorsement. Under 49 CFR 383.123, you must pass the passenger knowledge and skills tests, the school bus knowledge test, and a skills test in a school bus of your vehicle group.

T, doubles and triples. The manual says this is for Class A drivers who want to pull double or triple trailers.

Endorsements on a permit

You can add only three endorsements to a CLP: P, S and N (49 CFR 383.93(a)(2)). Federal rules prohibit all other endorsements on a CLP, so hazmat and doubles/triples wait until you hold a CDL (49 CFR 383.25(a)(5)(iv)).

A CLP with P or S cannot drive with passengers aboard, other than the CDL holder with you, test examiners, other trainees, and federal or state auditors and inspectors (49 CFR 383.25(a)(5)(i) and (ii)). A CLP with N may only drive an empty tank vehicle (49 CFR 383.25(a)(5)(iii)). To go from permit to license, see CDL permit to license: every step.

Which tests are you taking?

If you are not sure which endorsements your job needs, ask your employer or school. For Class A and B and the air brakes test, see which CDL tests you need.

Training rules differ by letter. H, P and S need ELDT the first time. N and T do not.

Extra endorsements can change which loads you take, and the break-even rate calculator shows the rate each load needs to cover your costs.

Your state sets how many questions each test has and the time limit. See how many questions are on each CDL test. The federal minimum passing score is 80% (49 CFR 383.135). For the H endorsement, see hazmat test questions by state.

Try 10 exam-style questions built from the official CDL manual.

How to study for endorsement tests

Each endorsement test covers one topic. Read only that manual section, plus the sections it points to. The tanker section, for example, tells you to also study Sections 2, 5, 6 and 9.

Take one practice test on the topic first. Read the answer explanations. Then study what you missed and test again. Every test type has a free 10-question practice test on the CDL practice test page.

Common questions

Which CDL endorsements need a written test?

All of them. 49 CFR 383.93(c) requires a knowledge test for double/triple trailers, passenger, tank vehicle, hazardous materials and school bus. The X endorsement is the tank vehicle and hazardous materials endorsements together, so it needs both knowledge tests. Passenger and school bus also need a skills test.

What is the X endorsement?

X is the combined tank vehicle and hazardous materials endorsement. 49 CFR 383.153 lists it as 'a combination of tank vehicle and hazardous materials endorsements.' The manual says drivers of tank vehicles who haul placarded hazardous materials or waste must add X, which shows they passed both knowledge tests.

Do I need the tanker endorsement to haul hazmat in a tank?

Yes, when the tank meets the manual's size rule and the load needs placards. The manual says those drivers must add the X endorsement, which covers both the tank vehicle and the hazardous materials tests. Ask your state licensing agency how it applies to your truck.