CDL Endorsements and Restrictions Explained
Updated October 27, 2026
An endorsement adds permission to drive a specific type of commercial vehicle. A restriction limits what you may drive, usually because of how you took your skills test. Here’s what each one means under federal rules (49 CFR 383).
Endorsements
| Code | Endorsement | Tests required |
|---|---|---|
| T | Double/triple trailers | Knowledge test |
| P | Passenger | Knowledge and skills test |
| N | Tank vehicle | Knowledge test |
| H | Hazardous materials | Knowledge test, plus a TSA security threat assessment |
| X | Tank vehicle and hazardous materials combined | Both the tank and hazmat requirements |
| S | School bus | Knowledge and skills test |
The only endorsements allowed on a commercial learner’s permit (CLP) are passenger, school bus and tank vehicle.
Common restrictions
| Restriction | Usually added when you… |
|---|---|
| No air brakes | Fail the air brakes knowledge test, or take the skills test in a vehicle without air brakes |
| No full air brakes | Take the skills test in a vehicle with air-over-hydraulic brakes |
| No manual transmission | Take the skills test in a vehicle with an automatic transmission |
| No tractor-trailer | Take a Class A skills test in a combination connected by a pintle hook instead of a fifth wheel |
| Passenger vehicle limits | Take the passenger skills test in a smaller class of bus than you want to drive |
Restriction letter codes vary in how states print them, so check your state’s CDL manual.
Practice
Try free questions for Hazmat, Doubles and Triples, Tank Vehicles, Passenger and School Bus. See also Class A vs B vs C.
Pass your CDL permit test on the first try
- All 215 questions for General Knowledge, Air Brakes, Combination Vehicles and Hazmat
- An explanation for every answer, from the CDL manual and federal rules
- Unlimited practice tests for each knowledge test, scored like the real one (80% to pass)