Commercial Driver's License (CDL)

By Javier Marín, Editor·Last reviewed September 2026·How we check this

A Commercial Driver's License is the federally regulated credential required to operate large trucks, buses, and certain hazardous-materials vehicles for hire. The framework is set by the Federal Motor Carrier Safety Administration (FMCSA); the test is administered and the license issued by your state DMV.

Anyone who drives a vehicle weighing 26,001 pounds or more, transports 16 or more passengers (including the driver), or hauls placarded amounts of hazardous materials needs a CDL. The classes are letter-coded:

The three CDL classes

Class A: Combination vehicles with a gross combined weight rating of 26,001 pounds or more, where the towed vehicle exceeds 10,000 pounds. This is the over-the-road tractor-trailer license.
Class B: Single vehicles 26,001+ pounds and combinations where the towed unit is 10,000 pounds or less. Box trucks, dump trucks, and most municipal buses fall here.
Class C: Vehicles below the Class B threshold that either carry 16+ passengers or haul placarded hazmat. Smaller passenger vans and certain hazardous-materials trucks use Class C.

Endorsements

Endorsements are letter codes added to a CDL that authorize specialized cargo or vehicle types. Each requires a separate written knowledge test, and some require a separate skills test:

H — Hazardous Materials. Requires a TSA threat-assessment background check.
N — Tank Vehicles.
X — Combined HazMat and Tank.
P — Passenger transport (16+).
S — School Bus. Requires P endorsement, a fingerprint check, and a state-specific training program.
T — Doubles/Triples (multiple trailers).

Entry-level driver training (ELDT)

Since February 2022, all new Class A and Class B applicants — and applicants for the H, P, and S endorsements — must complete an FMCSA-approved Entry-Level Driver Training program before taking the skills test. The training has both classroom (theory) and behind-the-wheel (range and on-road) components. There's no minimum hour requirement set by the federal rule, but the curriculum is detailed and most accredited schools complete it in 160 to 200 hours over four to eight weeks.

Medical certification

Every CDL holder must carry a current medical certificate from an examiner listed on the FMCSA's National Registry. The exam covers vision (20/40 corrected, with peripheral vision and color recognition for traffic-signal colors), hearing, blood pressure, and disqualifying conditions like uncontrolled diabetes, certain seizures, and current substance abuse. Certifications are typically valid for two years; less if the examiner notes a managed condition.

Skills test format

The CDL skills test has three parts taken in sequence:

Pre-trip inspection. A guided walk-around in which you identify and explain components — brakes, lights, leaks, coupling — to demonstrate you know what to check before a run.
Basic vehicle control. Straight-line backing, offset backing, and parallel parking with the kind of long combination vehicle most applicants haven't driven outside the school yard.
Road test. Driving on public roads with the examiner in the cab, scored on lane discipline, signaling, intersection handling, and freeway merging.

Failure on any one part typically requires retesting the failed part within a state-defined window, often 14 days, before the entire test resets.