Kristi Mauldin
Before you spend money on a CDL program — or before you hire a driver and wonder whether their license covers your freight — you need to understand exactly what each class and endorsement authorizes. The CDL system is not complicated once you strip away the jargon, but the gaps between classes and endorsements carry real consequences: put a Class B driver in a Class A configuration and you have a violation; send a driver hauling hazmat without the H endorsement and you have a federal problem.
This guide covers every class, every endorsement, the Entry-Level Driver Training requirement that catches a lot of new applicants off guard, and my honest take on which endorsements are undervalued.
CDL Class A: The Combination Vehicle License
Class A authorizes the operation of any combination vehicle with a gross combination weight rating (GCWR) of 26,001 pounds or more — provided the towed unit exceeds 10,000 pounds GVWR.
In practice, Class A is the standard license for:
- 18-wheelers and tractor-trailer combinations
- Semi-trucks pulling flatbeds, refrigerated trailers, dry vans, and tankers
- Doubles and triples (with the T endorsement)
- Any combination pulling a trailer over 10,000 lbs when the combined weight exceeds 26,001 lbs
Key fact: A Class A holder can also operate Class B and Class C vehicles, assuming they have any required endorsements for those vehicle types. This makes Class A the most versatile CDL to hold.
Class A is the license category most carriers prioritize in hiring. If you are an aspiring driver looking to maximize your employability from day one, Class A is the right target.
CDL Class B: Single Heavy Vehicle
Class B covers single vehicles with a GVWR of 26,001 pounds or more — and any towed unit that does not exceed 10,000 pounds GVWR.
Common Class B vehicles include:
- Straight trucks (box trucks, delivery trucks, dump trucks)
- Large buses
- Segmented buses
- Refuse/garbage trucks
- Some heavy construction vehicles operated on public roads
Class B is often the path for drivers focused on local or regional delivery, municipal operations, and certain construction or utility jobs. The limitation: a Class B license does not authorize pulling a heavy trailer. That distinction matters when a fleet needs drivers who can drive straight trucks and occasionally drop a trailer at a dock — Class A is the safer hire for flexibility.
Class B holders can also operate Class C vehicles with the appropriate endorsements.
CDL Class C: Smaller Vehicles, Specific Cargo or Passengers
Class C covers vehicles that do not meet the weight thresholds for Class A or B but are designed to transport either:
- 16 or more passengers (including the driver), or
- Hazardous materials in quantities requiring placarding
This class is most commonly associated with airport shuttle operations, smaller transit vehicles, and certain hazmat transport operations that use medium-duty vehicles. It is easy to underestimate — a driver hauling explosives or radioactive material in a standard pickup or cargo van may legally require a Class C CDL with the H endorsement depending on the quantity and type of hazmat.
CDL Endorsements: What Each One Authorizes
Endorsements are add-ons to a base CDL class, each requiring additional testing and, in some cases, federal background checks. Here is each endorsement and what it means operationally.
H — Hazardous Materials
The H endorsement authorizes the driver to haul hazardous materials in quantities that require placarding under 49 CFR.
What it requires:
- A knowledge test administered by the state
- A TSA security threat assessment (STA) — a federal background check that screens for disqualifying criminal history, immigration status, and terrorism-related concerns. This is not just a DMV transaction; TSA has approval authority.
- Renewal every five years (the TSA STA requires periodic renewal as well)
The H endorsement is the only CDL endorsement that involves a federal agency outside FMCSA. That alone tells you the government takes hazmat transport seriously.
I cover the full cost-benefit of hazmat hauling in the companion post on our services page. The short version: higher pay, higher compliance burden.
N — Tank Vehicles
The N endorsement authorizes the operation of tank vehicles — any vehicle designed to transport liquids or liquefied gases in a tank or tanks either permanently attached to the vehicle or carried on the vehicle.
The threshold that triggers the endorsement requirement: a tank with a capacity of 119 gallons or more of liquids or liquefied gas.
Tank vehicles include fuel tankers, chemical tankers, milk tankers, and liquid food-grade transport. Tank driving demands specific techniques — surge effects from partial loads, anti-rollover management, and tank inspection procedures — that the knowledge test and required skills test address.
X — Tank Vehicles Carrying Hazardous Materials
The X endorsement is the combination of N and H. It covers tank vehicles hauling hazardous materials in placardable quantities.
If you plan to haul fuel, certain chemicals, or other hazmat in a tanker, you need the X endorsement — not N alone, not H alone. Many drivers who haul petroleum products hold the X endorsement as their baseline.
T — Doubles and Triples
The T endorsement authorizes pulling double and triple trailers. It is required in addition to Class A.
Doubles and triples are common in certain regional freight networks and on designated highway corridors where state law permits triple combinations. The knowledge test covers coupling and uncoupling procedures, inspection requirements, and the different stability characteristics of these configurations.
P — Passenger
The P endorsement is required to operate vehicles designed to carry 16 or more passengers, including the driver. It requires both a knowledge test and a skills test conducted in the actual vehicle type.
Passenger endorsements are standard requirements for commercial bus drivers, motor coach operators, and large shuttle operators.
S — School Bus
The S endorsement is required to operate a school bus and must be held in addition to the P endorsement. It covers the additional operational and safety requirements specific to school bus operation: railroad crossing procedures, loading and unloading students, emergency exit protocols, and state-specific requirements.
The S endorsement requires a knowledge test, a skills test in a school bus, and — in most states — a background check for working with minors.
Entry-Level Driver Training (ELDT): What New Applicants Must Know
Since February 7, 2022, the FMCSA has required Entry-Level Driver Training (ELDT) for most applicants seeking:
- A Class A or Class B CDL for the first time
- An upgrade from Class B to Class A
- The H, N, X, P, or S endorsement for the first time
ELDT has two components: theory training (classroom or online) and behind-the-wheel (BTW) training — both must be completed with a provider listed on the FMCSA Training Provider Registry (TPR) at tpr.fmcsa.dot.gov.
There is no minimum hour requirement for most ELDT training — the regulation specifies curriculum outcomes, not seat time, with the exception of certain theory minimums. However, the training must be completed and reported to the TPR before the state will administer the CDL skills test.
Why this catches applicants off guard: Some aspiring drivers begin the process at the DMV and only then discover they need to complete ELDT at a registered provider before they can sit for the skills test. Starting with a registered CDL school or training program eliminates this delay.
Which Endorsements Pay Off
Most carriers and owner-operators focus on the Class A CDL and leave endorsements as a later consideration. That is a reasonable starting point, but it undersells the earning difference that endorsements create.
Hazmat (H or X): Higher freight rates, more load options, required for much of the fuel and chemical hauling market.
Tanker (N or X): Liquid bulk is a specialized market with steadier demand. Many fuel-hauling and chemical transport jobs require both N and H (i.e., X).
Doubles/Triples (T): Valued in certain regional and LTL networks. Less universally applicable than hazmat or tanker, but useful in specific markets.
Passenger (P) and School Bus (S): Strong local demand in many markets; useful for drivers seeking stable, schedule-driven work.
The Endorsement Most Owner-Operators Underrate
My opinion: the N endorsement (tanker) is the most underrated endorsement for owner-operators.
Most drivers pursuing additional credentials go straight for hazmat — and hazmat is valuable. But tanker-only positions (non-hazmat liquid transport: water, food-grade, non-regulated chemicals) are plentiful, often local or regional, and frequently overlooked because “tanker” gets mentally bundled with hazmat. They are separate endorsements. A driver with the N endorsement and no H can still tap into a meaningful portion of the liquid bulk market without the TSA background check, the additional liability exposure, and the compliance overhead of full hazmat compliance. For an owner-operator building a book of business, the N endorsement opens doors that a straight Class A does not — with a shorter path to getting there.
Frequently Asked Questions
Q: Can a Class A CDL holder drive Class B and C vehicles? Yes. A Class A license authorizes the operation of Class B and Class C vehicles as well, assuming any required endorsements are held. The reverse is not true — a Class B holder cannot operate Class A combination configurations.
Q: Does the ELDT requirement apply to me if I am upgrading from Class B to Class A? Yes. An upgrade from a Class B to a Class A CDL triggers the ELDT requirement. You must complete training with a provider on the FMCSA Training Provider Registry before your state will schedule the skills test.
Q: How long does the TSA background check for the H endorsement take? Processing times vary, but applicants should plan for several weeks. The TSA administers this check independently of the state DMV process, and applicants apply directly through the TSA. Delays are not uncommon during high-volume periods.
Q: Do endorsements expire separately from the CDL? CDL expiration is set by the state and typically covers the entire license including endorsements. However, the TSA security threat assessment for the H endorsement has its own renewal cycle. Check your state’s specific requirements, as some endorsements may require periodic knowledge test renewal.
Q: Can I add multiple endorsements to an existing CDL? Yes. Endorsements are added to a base CDL class, and you can hold multiple endorsements simultaneously. Adding an endorsement typically requires passing the relevant knowledge test (and in some cases a skills test) and meeting any additional federal requirements, such as the TSA check for hazmat.
Ready to Maximize Your CDL Credentials or Hire Smarter?
Whether you are planning your CDL path or building a driver onboarding program that matches license classes to your freight, getting the credentials right from the start prevents costly compliance mistakes later.
Book a free consultation with Logistics Assistance Now. We help owner-operators and carriers align driver qualifications with operational needs — and make sure the compliance documentation is in order from day one. Learn more about our services for independent contractors or explore the full range of compliance and training services we offer to carriers and fleets of all sizes.
Disclaimer: CDL requirements, endorsement rules, and ELDT regulations may be updated by FMCSA or individual state licensing agencies. Always verify current requirements with your state’s CDL licensing authority or consult a qualified compliance professional.
