When it comes to professional driving, a Class A Commercial Driver’s License (CDL) opens the door to a wide range of opportunities in the transportation industry. From long-haul trucking to specialized freight, Class A CDL holders are among the most in-demand professionals on the road.

But not all CDL holders are qualified to drive every type of commercial vehicle or haul every kind of load. To legally and safely operate certain vehicles or transport specific types of cargo, drivers must obtain endorsements, special authorizations added to their CDL.

In this guide, we’ll break down what endorsements are, which ones are most commonly required for Class A CDL drivers, and how your trucking company can help employees earn them efficiently.

What Are CDL Endorsements?

A CDL endorsement is an additional qualification that allows a commercial driver to operate specialized vehicles or haul specific types of freight that go beyond the basic CDL class requirements.

Endorsements are regulated by the Federal Motor Carrier Safety Administration (FMCSA) and individual state DMVs, ensuring that anyone operating a commercial motor vehicle is properly trained and certified.

These endorsements appear as letter codes on a driver’s CDL and indicate that they’ve passed specific tests, written, skills-based, or both, that demonstrate their ability to safely handle additional driving responsibilities.

For instance, handling a tanker or hazardous load requires understanding complex safety procedures, load balance, and gross vehicle weight rating (GVWR) limits to remain compliant.

A driver might hold a Class A CDL with multiple endorsements such as a hazmat endorsement (H) for hazardous materials, a tanker endorsement (N) for liquid cargo, and a doubles/triples (T) endorsement for combination vehicles. With these credentials, they’re legally authorized to haul multiple trailers, liquid tankers, or hazardous freight across state lines.

While Class A CDL holders typically manage the largest vehicles and combinations, Class B CDL holders may also pursue certain endorsements to expand their opportunities. For example, adding a hazmat endorsement or operating a class B passenger vehicle such as a large bus.

Similarly, Class C CDL holders often add endorsements that allow them to drive smaller passenger or hazardous material vehicles, such as a class C passenger vehicle used for shuttle transport or specialized deliveries.

In short, endorsements enhance the flexibility of all CDL class drivers, from Class B CDL holders managing local routes to Class C CDL holders serving niche markets, by certifying them to safely operate different vehicle types and meet the evolving demands of the transportation industry.

Who Needs a Class A CDL?

A Class A CDL is required for anyone operating a combination vehicle with a gross combination weight rating (GCWR) of 26,001 pounds or more, provided that the towed vehicle exceeds 10,000 pounds.

This includes:

• Tractor-trailers (18-wheelers)

• Livestock carriers

• Flatbeds and reefers

• Tanker trucks

• Double and triple trailers

It’s the foundation of most trucking company fleets and represents the first step for drivers looking to build a long-term career in transportation.

The Most Common Class A CDL Endorsements

Let’s take a closer look at the main endorsements available to Class A CDL holders, what each allows, and what endorsement requirements or CDL training may be needed before a driver can legally operate these specialized vehicles.

Obtaining the appropriate endorsements ensures compliance with federal guidelines and helps drivers advance within different CDL classes.

T Endorsement – Double/Triple Trailers

Allows you to: Tow two or three trailers (long combination vehicle towing).
Test required: Written knowledge test only.

Drivers who haul multiple trailers are in high demand because it takes precision, balance, and skill to manage long configurations safely. Many large trucking companies offer premium pay for drivers with the T endorsement.

However, not all states permit triple trailers, so dispatchers and recruiters must verify route legality before assigning these loads.

N Endorsement – Tank Vehicles

Allows you to: Operate a tanker vehicle designed to transport liquid or gaseous materials in tanks exceeding 119 gallons.
Test required: Written knowledge test only.

The N endorsement is vital for anyone hauling fuel, milk, or chemicals. Handling liquids adds extra risk, as shifting weight affects braking and control.

Quality CDL training covers surge control, braking techniques, and understanding systems such as air brakes or hydraulic brakes. Proper awareness of gross vehicle weight rating (GVWR) and full air brakes capacity is essential for driver safety.

H Endorsement – Hazardous Materials (HazMat)

Allows you to: Transport hazardous materials requiring placards under federal law.
Test required: Written knowledge test, TSA background check, and fingerprinting.

The hazardous materials endorsement, sometimes listed as H Hazardous Materials, is one of the most valuable a driver can earn. It allows transport of fuels, chemicals, and other regulated cargo but also requires thorough security clearance and renewal every five years.

Many Class B CDL holders and Class C trucks operators also pursue this endorsement prior to upgrading to a Class A license to broaden their hauling options.

X Endorsement – Tanker and HazMat Combination

Allows you to: Operate a tank vehicle carrying hazardous materials.
Test required: Combination of the N and H tests plus a background check.

This combined hazardous materials endorsement and tanker endorsement enables drivers to haul liquid hazardous freight under one certification. Because it satisfies multiple endorsement permits, many fleets require or reward it.

Holding the X endorsement shows a driver can manage complex single vehicle or combination setups with strong understanding of both chemical safety and fluid dynamics.

P Endorsement – Passenger Vehicles

Allows you to: Transport passengers in vehicles designed for 16 or more people (including the driver).
Test required: Written knowledge test and skills test.

A passenger endorsement is essential for anyone working in passenger transport, such as charter buses or delivery services that occasionally move groups of employees.

Although long-haul freight drivers rarely need it, this credential is valuable for cross-training or seasonal assignments. It also applies to Class C vehicles used in shuttle or corporate transport operations.

S Endorsement – School Bus

Allows you to: Drive school buses transporting students.
Test required: Written knowledge test, skills test, background check, and driving-record review.

To earn an S endorsement, a driver must already hold a passenger endorsement. This ensures proper safety standards for youth and school-sponsored events.

Training includes additional tests on student pickup procedures, emergency protocols, and vehicle inspection routines. These drivers may come from Class C CDL holders or Class B CDL holders operating buses and straight trucks city routes before upgrading to a Class A license.

Holding the correct endorsements empowers drivers to expand their careers within different CDL classes, from Class C vehicles and buses to interstate tanker and hazmat freight. Each credential reflects mastery of unique skills, from manual transmission control to air brakes awareness, and ensures drivers can legally operate their chosen equipment under federal guidelines.

Preparing for CDL Endorsement Tests

Most endorsements require passing at least one written test, while others, like the passenger or school bus endorsements, also require a road test.

To prepare effectively, drivers should:

• Study the state CDL manual’s endorsement sections thoroughly.

• Take online practice tests available on DMV or trucking company websites.

• Enroll in a certified CDL training program that includes endorsement preparation.

• Confirm that all identification, background, and medical documents are up to date.

HR teams and recruiters can support employees by reimbursing testing fees, offering paid study time, or connecting new hires with trusted local training partners. Helping drivers expand their credentials benefits both the individual and the company, increasing capacity, reducing hiring gaps, and improving overall efficiency.

The Business Benefits of Endorsed Drivers

For a trucking company, having drivers with multiple endorsements means greater flexibility, better utilization, and less downtime. It allows dispatchers to assign a wider range of loads, helping to avoid idle trucks and missed opportunities.

It also builds resilience in operations. If one driver is unavailable or a specialized load needs coverage, having qualified backups ensures smooth continuity. Moreover, drivers with additional endorsements often earn higher pay and stay longer, reducing turnover costs and improving morale among your employees.

Compliance and Renewal

Endorsements are not permanent. Depending on your state, most endorsements must be renewed when the CDL itself is renewed, typically every 5 to 8 years. HazMat (H and X) endorsements require periodic tests and TSA re-clearance.

Fleet managers should use compliance software or a company website dashboard to track expiration dates, send reminders, and maintain digital copies of credentials. This ensures drivers stay compliant and reduces the risk of fines or suspensions.

Obtaining the right endorsements is a crucial step for any commercial driver aiming to advance their careers, and for every trucking company that wants to stay competitive, compliant, and efficient.

Whether it’s the T for doubles/triples, N for tankers, or the X combination for maximum flexibility, each endorsement opens new opportunities. For HR teams and recruiters, encouraging drivers to pursue these qualifications not only builds individual skill but also strengthens the entire fleet’s capability and reputation.

At the end of the day, CDL training doesn’t end with the license, it’s an ongoing journey of growth, safety, and professionalism that keeps America’s transportation network moving forward.