What Are CDL Endorsements and Restrictions?
If you’re exploring a career in commercial truck driving, chances are you know you need a commercial driver’s license (CDL) A, B, or C. But, did you know these licenses can be added to—or subtracted from—depending on factors like training, age, and more?
This page will explore CDL endorsements and restrictions—the additions and subtractions. You’ll learn what these terms mean, how you can obtain them, and, in the case of restrictions, how you can have them removed.
What Are CDL Endorsements?
CDL endorsements are certifications allowing you to drive certain types of commercial vehicles CDLs alone don’t. Each endorsement requires a knowledge test, and some require a skills test as well. Adding endorsements to your CDL could be a great way to advance your career and be in a position to earn a higher salary.
You can obtain just one endorsement, or you can get several. The more you have, the more options you may have for truck driving jobs.
How Many CDL Endorsements Are There?
There are six common types of CDL endorsements—though more may be available depending on your state. (Your state may also have different codes for these endorsements.)
| CDL Endorsement | What it Lets You Do | Minimum CDL You Need |
| H | Drive vehicles with hazardous materials (HAZMAT) | CDL C |
| N | Operate tank vehicles that contain liquids or gases | CDL B |
| P | Drive passenger vehicles with 16 or more seats | CDL C |
| S | Operate a school bus | CDL C |
| T | Drive a double or triple trailer truck | CDL B |
| X | Drive both a tank truck and hazardous materials (combination of H and N) | CDL B |
The CDLs mentioned above are the minimum—you can have the “higher” levels of CDLs and obtain those same endorsements. This is because CDLs A and B often also allow you to drive the levels “below” them. However, some are more common to obtain than others depending on your CDL—it’s rarer for CDL A drivers to go for their S endorsement, for instance.
Below is more information about each type of endorsement. This information is general—your state may have laws changing the details. If you have an endorsement that expires before your CDL does, you can reapply when the endorsement period is about to end.
CDL H Endorsement: For driving hazardous materials
Additional Training
Training involves learning about the hazardous materials you’ll be transporting, covers your role as a HAZMAT driver, provides safety training on how to recognize potential dangers, and includes security training because of the dangerous nature of the materials. Additional CDL endorsements are needed to drive a tank truck containing hazardous materials (see CDL X endorsement).
Required Tests
Written knowledge test; TSA Security Threat Assessment application; fingerprinting; background check
Endorsement Length
No more than five years after the Security Threat Assessment application is approved
Because of the dangerous nature of hazardous materials, HAZMAT is one of the most challenging CDL endorsements to achieve. Once you have this endorsement, you’ll be able to work with a variety of companies like chemical manufacturers, metal producers, and petroleum processors to drive their materials to clients or between facilities.
CDL N Endorsement: To operate tank vehicles with liquids or gases
Additional Training
Training involves inspection of tank vehicles, specific challenges of hauling liquids (e.g., movement of materials, higher center of gravity), and safety rules.
Required Tests
Written knowledge test
Endorsement Length
As long as your CDL is valid
Driving a tank truck containing liquids requires different skills that involve understanding the movement of liquids and the higher center of gravity the content has. Being able to haul liquids in addition to dry goods means that your CDL license could open up more employment opportunities.
CDL P Endorsement: To drive passenger vehicles with 16 or more seats
Additional Training
Training involves pre- and post-trip vehicle inspection, vehicle loading and trip start practices, road safety and stops, prohibited practices, and use of specific equipment.
Required Tests
Written knowledge and road skills tests
Endorsement Length
As long as your CDL is valid
The CDL P endorsement allows you to operate a bus or passenger vehicle with 16 or more people (including the driver), including city buses and tour buses. Because people are also the “cargo” in your job, you’re trained to understand and manage the equipment and to handle people you’re charged with keeping safe.
CDL S Endorsement: To operate a school bus
Additional Training
Training involves the use of mirrors, understanding danger zones where children are most likely to be hit by a car, emergency procedures, railroad-highway grade crossings, student management, anti-lock brakes, and special safety considerations of these vehicles.
Required Tests
Written knowledge test, road skills test, background check
Endorsement Length
As long as your CDL is valid
School bus drivers have the most precious cargo: children. Additionally, this endorsement allows you to transport large numbers of passengers regardless of age. Not only do you need to understand the specific functions of the bus, but you’re also charged with keeping children safe every day, so you’ll be trained to handle the unique issues that come with driving this population.
CDL T Endorsement: To drive a double or triple trailer
Additional Training
Training involves the specific skills and risks of pulling a double or triple trailer (e.g., preventing rolling over, knowledge about the crack-the-whip effect), how to couple and uncouple the trailers, inspections, and checking air brakes.
Required Tests
Written knowledge test
Endorsement Length
As long as your CDL is valid
Doubles and triples aren’t only heavier than standard trucks, but they also risk rolling over and have special challenges in adverse situations such as slippery roads and bad weather. Because double or triples allow companies to haul more cargo, drivers with CDL T endorsements are in fairly high demand.
CDL X Endorsement: To drive both a tank truck and hazardous materials
Additional Training
This involves both HAZMAT and tank truck tests.
Required Tests
Written knowledge test, background check
Endorsement Length
No more than five years after the Security Threat Assessment application is approved
Because many hazardous materials are hauled by tank trucks, this endorsement—which is a combination of both H and N endorsements—gives you even more flexibility to haul needed cargo.
What Are CDL Restrictions?
CDL restrictions apply to your overarching license and indicate the types of vehicles you aren’t allowed to operate.
Restrictions may be applied to your CDL for a variety of reasons, which aren’t always a reflection of lesser driving skill. For instance, younger drivers (usually between the ages of 18 and 21) sometimes automatically have certain restrictions—this varies by state. There may also be medical issues making operating certain types of vehicles difficult.
However, not passing a certain portion of an exam or taking a test on a vehicle that didn’t have specific equipment that you need to prove you have experience with may restrict your CDL.
How Many CDL Restrictions Are There?
There are seven common CDL restrictions, but your state may have different laws, letters identifying these restrictions, or additional restrictions. Most of these restrictions can be lifted.
| CDL Restriction | What it Restricts | Type of CDL it Applies To |
| E | You may not drive a vehicle with manual transmission. | Class A, B, and C CDL |
| L | You may not use full air brakes. | Class A, B, and C CDL |
| M | You can only operate a Class B or C passenger vehicle or school bus, no Class A passenger vehicles. | Class A CDL |
| N | You can only operate a Class C passenger vehicle or school bus, not a Class B one. | Class B CDL |
| O | You can’t drive a Class A vehicle with a fifth-wheel connection. | Class A CDL |
| V | You have medical variance (or exemption) reported to the FMCSA. | Class A, B, and C CDL |
| Z | You may not use full air brakes. | Class A, B, and C CDL |
CDL E Restriction: May not drive a vehicle with manual transmission
If you take your CDL skills test in a vehicle with automatic transmission, you won’t be allowed to operate vehicles with manual transmission. Because it limits the potential types of vehicles you can operate, you may want to take your test—or an additional test—with the appropriate vehicle to lift the restriction. Of course, to take this test, you’ll need to learn how to drive a manual transmission vehicle, which might depend on what your employer or school has available for you to practice on.
CDL L Restriction: May not use full air brakes
This restriction means you didn’t pass the full air brake test. This could hurt job opportunities because many vehicles have full air brake systems, and understanding them is essential for road safety. You can retake your test multiple times. Once you pass the air brake portion, you can have the restriction lifted.
CDL M Restriction: Can only operate a Class B or C passenger vehicle or school bus, no Class A passenger vehicles
Admittedly, this is a confusing one. This means that under your Class A license, you received your passenger or school bus endorsement in a Class B vehicle. Consequently, you’re restricted to only driving those types of passenger vehicles—no class A ones. Class A passenger vehicles are typically articulated buses, also known as “bendy buses.” You’ll likely have to take the knowledge and road skills tests to have the restriction lifted; but, if you don’t want to drive an articulated bus, you probably don’t need to worry about this.
You can still drive other Class A vehicles.
CDL N Restriction: Can only operate a Class C passenger vehicle or school bus, not a Class B one
Like the CDL M restriction, this can be puzzling at first glance. In this case, you have a Class B CDL license but received passenger/bus endorsement in a Class C vehicle. Class C passenger vehicles are smaller, and if you want to drive larger passenger vehicles, you need to have this restriction lifted. You can do that by taking the knowledge and road skills test on the appropriate vehicle.
You can still drive other Class B vehicles.
CDL O Restriction: May not drive a Class A vehicle with a fifth-wheel connection
If you take your skills test in a vehicle with a pintle hook, gooseneck, ball and chain hook up, or any other vehicle with a non-fifth wheel connection, you’ll have this restriction. A “fifth wheel” connection hooks your truck to what it’s towing. A CDL O restriction is are a pretty big deal, as it means you generally can’t drive a semi-truck with an attached trailer, and you should consider getting it lifted. To get the restriction lifted, you’ll need to take the skills test in an appropriate vehicle.
CDL V Restriction: Has medical variance (or exemption) reported to the FMCSA
A medical variance indicates that you have a medical condition that must be reported to the Federal Motor Carrier Administration (FMCSA). You’re allowed to continue driving commercially, but you must keep your records with the FMCSA current to ensure that you’re qualified to drive. If your medical condition can be treated or cured, work to do so.
CDL Z Restriction: May not use full air brakes
This restricts the same thing as the Class L restriction—your ability to use full air brakes—but the reason for the restriction is different. You’ll have a Z restriction placed on your CDL license if you take your exam on a vehicle with a hydraulic brake system. This may not be an issue if the company you work for doesn’t have full air brakes, but if you want this restriction lifted, you’ll need to be trained on and take the exam with a vehicle with such a system.