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A commercial driver’s license (CDL) is defined as a license which authorizes the individual to operate a class of a commercial motor vehicle (CMV). Additionally, commercial learner’s permit (CLP) is defined as a permit authorizing an individual to operate a class of a CMV when accompanied by a holder of a valid CDL for purposes of behind-the-wheel training. There are three distinct classes of CDL:

  • Class A - A driver holding a Class A license can also operate both Class B and C vehicles.

  • Class B - A driver holding a Class B license can operate a Class C vehicle but not a Class A vehicle.

  • Class C - A driver holding a Class C license can only operate a Class C vehicle.

It is important to note that not every CMV driver is required to have a CDL or CLP. As the previous definitions indicate, a CDL or CLP is necessary to operate “a class” of a CMV.

With this in mind, the FMSCA states the CDL/CLP standards apply to “commercial motor vehicles” operating in interstate, intrastate, or foreign commerce that meet one or more of the following standards:

  • Combination vehicles having a gross combination weight rating or gross combination weight (whichever is greater) of 26,001 or more pounds and having one or more towed units with a gross vehicle weight rating or gross vehicle weight (whichever is greater) of more than 10,000 pounds.

  • Single unit vehicles having a gross vehicle weight or gross vehicle weight rating of 26,001 pounds or more.

  • Buses designed to transport 16 or more passengers, including the driver.

  • Hazmat used in the transportation of hazardous materials that require notice on the vehicle.

The FMCSA specified eight exemptions to the CDL/CLP standards. These exemptions are as follows:

  1. States must exempt drivers who operate CMVs for military purposes.

  2. States must exempt driver of “covered farm vehicles”

  3. States may exempt drivers of farm vehicles that are controlled and operated by a farmer (further specifications for this exemption are found in the FMCSRs).

  4. States may exempt firefighters and other persons who operate CMVs necessary to save lives.

  5. States may exempt drivers employed by the local government to remove snow or ice.

  6. There is an exemption for Alaska drivers.

  7. States may issue restricted CDLs for employees of a farm-related service industry.

  8. States may issue restricted CDLs to part-time drivers carrying less than 500 pounds of fireworks.


Drivers are required to obtain CDL endorsements in order to operate certain types of vehicles. The FMCSRs identify these endorsements with a code in the form of a single capital letter. These endorsements include:

  • T Double and triple trailers

  • P Passenger vehicles

  • N Tank vehicles

  • H Vehicles required to have identification indicating there are hazardous materials on board

  • S School buses

  • X A combination of N and H endorsements

These endorsements are the only ones identified by the FMSCA but an individual state may have more. In order to get endorsement for any of the ones listed, a driver must pass a knowledge test. In addition to a knowledge test, S and P endorsements require a skills test. Furthermore, a background check is required for H endorsement.

While endorsements allow for the operation of certain types of vehicles, the FMCSA has also outlined eight restrictions that prevent certain types of operations. Like endorsements, these restrictions are identified with different codes and they include:

  • E - If a driver performs the skills test in an automatic transmission vehicle, he or she cannot operate a CMV equipped with manual transmission.

  • K - If a driver is not qualified to drive interstate, he or she is restricted from driving outside the state.

  • L - If a driver either fails the air brake component of the knowledge test or performs the skills test in a vehicle not equipped with air brakes, he or she cannot operate a CMV with air brakes.

  • M - If a driver performs the skills test in a Class B vehicle, he or she cannot operate a Class A vehicle.

  • N - If a driver performs the skills test in a Class C vehicle, he or she cannot operate a Class A or B vehicle.

  • O - A driver who did not perform a skills test in a tractor-trailer combination connection by a fifth wheel cannot operate one.

  • V - A driver who was issued a medical variance has to have a restriction code “V” in their driver’s record.

Z - If a driver performs the skills test in a vehicle with air-over-hydraulic brakes, he or she cannot operate a vehicle with any braking system operating fully on the air-brake principle.