CDL endorsements are T (doubles and triples), P (passenger), N (tank vehicle), H (hazardous materials), X (tank plus hazmat) and S (school bus). T, N and H need a knowledge test; P and S also need a skills test; H also needs a TSA security check.
An endorsement is an add-on to your CDL that lets you drive a special kind of vehicle or load. Federal rules define six codes, and the state may issue them only after you pass the required tests. 49 CFR 383.9349 CFR 383.153
| Code | Endorsement | What it allows | Tests | Extra requirements |
|---|---|---|---|---|
| T | Double/triple trailers | Pulling double or triple trailers | Knowledge | Not allowed on a permit |
| P | Passenger | Carrying passengers in a passenger vehicle of your class | Knowledge and skills | Skills test in a passenger vehicle; first-time training required |
| N | Tank vehicle | Hauling liquid or gas in a tank of more than 119 gallons, with 1,000 gallons or more in total | Knowledge | Allowed on a permit for empty tanks only |
| H | Hazardous materials | Hauling hazardous materials that need placards | Knowledge | Security threat assessment or valid TWIC; first-time training required |
| X | Tank and hazardous materials combined | Both of the above in one code | Knowledge tests for N and H | Same as N and H |
| S | School bus | Driving a school bus | Knowledge and skills | Must pass the P tests too; first-time training required |
Air brakes are not an endorsement. If you fail the air brake knowledge test or take your skills test in a vehicle without them, your license is restricted instead. 49 CFR 383.95
The H endorsement has an extra federal check that no other endorsement has. A state may not issue, renew, upgrade or transfer it unless the Transportation Security Administration decides you are not a security risk, or you hold a valid TWIC. 49 CFR 383.141
Only three endorsements can be placed on a commercial learner's permit, and each comes with limits. 49 CFR 383.9349 CFR 383.25
The training rule names three endorsements. T and N have no training requirement under this rule. 49 CFR 380.609
| Endorsement | Training needed? | Before which test |
|---|---|---|
| P | Yes, first time only | Skills test |
| S | Yes, first time only | Skills test |
| H | Yes, first time only | Knowledge test |
| T, N, X | No separate training under this rule | Not applicable |
Drivers who held a P, S or H endorsement before February 7, 2022 are not required to complete the training for it. 49 CFR 380.603
| Code | Meaning | How you get it |
|---|---|---|
| L | No air brake equipped CMV | Failing the air brake knowledge test, or testing in a vehicle without air brakes |
| Z | No full air brake equipped CMV | Testing in a vehicle with air over hydraulic brakes |
| E | No manual transmission equipped CMV | Testing in a vehicle with an automatic transmission |
| O | No tractor-trailer CMV | Testing in a Class A combination joined by a pintle hook or any hitch that is not a fifth wheel |
| M | No Class A passenger vehicle | P test taken in a vehicle needing a Class B CDL |
| N | No Class A or B passenger vehicle | P test taken in a vehicle needing a Class C CDL |
| K | Intrastate only | Licensed for intrastate driving only; state rules decide who qualifies |
| V | Medical variance | A medical variance is on your driver record |
Note that code N on the restriction line is different from the N endorsement. States may add their own codes if they explain them on the license. 49 CFR 383.153
| Practice test | Prepares you for | Federal basis |
|---|---|---|
| General Knowledge | The knowledge test every applicant takes, and the CLP | Every CMV driver needs the 20 general areas |
| Air Brakes | The air brake knowledge test; failing it leads to restriction L | Seven air brake areas |
| Combination Vehicles | The combination vehicles test required for Class A | Failing it blocks a Group A permit or license |
| Doubles and Triples | The T endorsement | Knowledge test only |
| Tank Vehicles | The N endorsement, and half of X | Knowledge test only |
| Hazardous Materials | The H endorsement, and half of X | Knowledge test, plus TSA screening |
| Passenger Transport | The knowledge part of the P endorsement | A skills test follows |
| School Bus | The knowledge part of the S endorsement | P tests and a skills test also needed |
Federal rules set the passing mark for every knowledge test at 80 percent correct. 49 CFR 383.135
695 questions across all eight tests, with gauges, placards, signs and warning sounds. No account needed.
Start a CDL practice test →Federal rules list six endorsement codes: T for double and triple trailers, P for passenger, N for tank vehicle, H for hazardous materials, X for a tank and hazardous materials combination, and S for school bus. 49 CFR 383.153
Only passenger (P) and school bus (S). The T, N and H endorsements require a knowledge test only. For P and S, the skills test must be taken in a passenger vehicle or school bus of the group you want. 49 CFR 383.93
Yes. A state cannot issue, renew, upgrade or transfer an H endorsement unless the Transportation Security Administration finds you are not a security risk, or you hold a valid TWIC. The screening repeats at least every 5 years. 49 CFR 383.141
Only passenger (P), school bus (S) and tank vehicle (N). Passenger and school bus permit holders may not carry passengers other than the people the rule lists, and N allows empty tank vehicles only. All other endorsements are prohibited. 49 CFR 383.2549 CFR 383.93
No. Federal rules treat air brakes as a restriction. If you fail the air brake knowledge test or take the skills test in a vehicle without air brakes, your license shows restriction L. 49 CFR 383.9549 CFR 383.153
X is the code printed on a license for the combination of the tank vehicle (N) and hazardous materials (H) endorsements. It lets you haul hazardous materials in a tank vehicle. 49 CFR 383.153
For the first time you get a passenger, school bus or hazardous materials endorsement, you need training from a provider on the Training Provider Registry. Training for P and S comes before the skills test, and for H before the knowledge test. 49 CFR 380.60949 CFR 383.71
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