CDL Classes, Endorsements and Restrictions Explained

Whether a driver needs a commercial driver's license (CDL), and which class, depends on the vehicle, not the job title. The federal definitions in 49 CFR 383 turn on weight ratings, towed weight, passenger capacity and hazardous materials. This guide walks through the three license classes, the endorsements that sit on top of them, and the restrictions that can be printed on a license. This matters to every commercial driver, whether the goal is a Class A CDL for tractor-trailers or a lower class for smaller trucks.

Which Class Does a Vehicle Fall Into?

49 CFR 383.91 and the definition of "commercial motor vehicle" in 383.5 sort vehicles into three groups. The questions below follow that order.

Sorting a vehicle into a commercial motor vehicle group under 49 CFR 383.5 and 383.91.

Group	Name in the rule	Definition (paraphrased)
A	Combination Vehicle	A combination with a gross combination weight rating of 26,001 pounds or more (11,794 kg), where the vehicle being towed is rated above 10,000 pounds (4,536 kg).
B	Heavy Straight Vehicle	A single vehicle with a gross vehicle weight rating of 26,001 pounds or more, or such a vehicle towing a unit of not more than 10,000 pounds.
C	Small Vehicle	A vehicle that is neither A nor B but is designed to carry 16 or more passengers including the driver, or is used to transport hazardous materials as defined in 383.5.

Section 383.5 says "whichever is greater" for the rating and the actual weight, so a vehicle can fall into a group because of its actual weight even if the rating is lower. A driver who has passed the tests for a combination vehicle (A) may operate a heavy straight vehicle (B) or small vehicle (C), provided they hold any needed endorsement. A driver who has passed for B may operate C. Moving the other way means retaking the related tests.

Endorsements

An endorsement is an extra qualification added to a CDL. Under 383.93, a driver needs one to operate a vehicle that is:

Code	Endorsement	Test required
T	Double/triple trailers	Knowledge test
P	Passenger	Knowledge and skills test
N	Tank vehicle	Knowledge test
H	Hazardous materials	Knowledge test
X	Combined tank vehicle and hazardous materials	Both the N and H tests
S	School bus	Knowledge and skills test

Two points are worth noting. The code X is not a separate test; it records that the driver holds both tank and hazmat endorsements (383.153). On a commercial learner's permit (CLP), the only endorsements allowed are passenger, school bus and tank vehicle. The rule notes that a CLP holder with an N endorsement may only drive an empty tank vehicle. It must not have previously held hazardous materials unless it has been purged.

Restrictions Printed on a License

A license can carry restriction codes that reflect the vehicle used in the skills test. Under 383.95 and 383.153, examples include:

L: no air-brake equipped CMV, applied if the applicant fails the air brake knowledge test or takes the skills test in a vehicle without air brakes.
Z: no full air-brake equipped CMV, applied if the skills test was taken in a vehicle with air-over-hydraulic brakes.
E: no manual transmission CMV, applied if the skills test was taken in an automatic.
O: no tractor-trailer CMV, applied if a Group A skills test was done with a non-fifth-wheel connection such as a pintle hook.
K: intrastate only. V: medical variance.

A driver who plans to haul tractor-trailers should take the skills test in the right vehicle, because taking it in the wrong one can cost privileges they would otherwise have earned.

Training and Age

Entry-level driver training. Under 49 CFR 380.603, the training rules apply to entry-level drivers. Section 380.605 defines them as people who must take the CDL skills test for one of three reasons: to get a CDL for the first time, to upgrade to Class A or B, or to add a passenger, school bus or hazardous materials endorsement for the first time. Drivers who got the CDL or endorsement before 7 February 2022 are not required to comply for that credential. A CLP obtained on or after that date brings the training requirement with it. Except for the H endorsement, the theory and behind-the-wheel portions must be completed within one year of completing the first portion.
Minimum age. Under 49 CFR 391.11(b)(1), a person must be at least 21 years old to be qualified to drive a commercial motor vehicle, except as allowed in subpart G of that part. For drivers in interstate commerce, that means 21 or older.

State fees, test scheduling and the exceptions in 49 CFR 383.3 (certain farm, military and emergency uses) are left out here. So is medical certification, which Commercial Vehicle Roadside Inspections: What Each Level Covers touches on.

Frequently Asked Questions

Do I need a CDL for a vehicle rated under 26,001 pounds?

Possibly. A vehicle under that rating can still be a Group C commercial motor vehicle. It qualifies if it is designed to carry 16 or more passengers including the driver, or is used to transport hazardous materials as defined in 383.5.

Can a Class A driver operate a Class B vehicle?

Yes. Under 383.91(c), a driver who passed the tests for a combination vehicle may operate a heavy straight vehicle or small vehicle, as long as they have the endorsements required for it.

What does the X endorsement mean?

It is the license code for a driver who holds both the tank vehicle and hazardous materials endorsements, as listed in 383.153.

Why does my license say "no tractor-trailer"?

That is restriction O. It is applied if the Group A skills test was taken with the power unit and towed unit connected by a pintle hook or other non-fifth-wheel connection.

What can I drive with a Class A CDL?

A Class A (Group A) CDL covers combination vehicles with a combined rating of 26,001 pounds or more towing a unit rated above 10,000 pounds. Under 383.91(c), a driver who has passed the Group A tests may also operate a Group B or Group C vehicle, provided they hold the endorsements required for it.