What Is a CDL?
A Commercial Driver's License (CDL) is required to operate large, heavy, or placarded hazardous material vehicles in the United States. CDLs are issued by individual states but must meet federal FMCSA minimum standards, meaning a CDL from one state is valid in all states.
CDL Classes — A, B, and C
| Class | Vehicle Type | GVWR | Common Uses |
|---|---|---|---|
| Class A | Combination vehicles | 26,001+ lbs with towed vehicle over 10,000 lbs | Semi-trucks, tankers, flatbeds, livestock |
| Class B | Single large vehicles | 26,001+ lbs with towed vehicle under 10,000 lbs | Dump trucks, buses, box trucks, straight trucks |
| Class C | Small vehicles carrying 16+ passengers or hazmat | Under 26,001 lbs | Passenger vans, small hazmat vehicles |
Most over-the-road truck drivers need a Class A CDL. This is the most versatile license and allows you to drive Class B and C vehicles as well.
CDL Endorsements
Endorsements are additional qualifications added to your CDL for specialized vehicle types:
- H — Hazardous Materials — required to transport placarded hazmat. Requires TSA background check and knowledge test
- N — Tank Vehicles — required to drive tanker trucks. Knowledge test required
- T — Double/Triple Trailers — required to pull double or triple trailers. Knowledge test required
- P — Passenger — required to drive vehicles with 16+ passengers. Knowledge and skills tests required
- S — School Bus — required to drive school buses. Knowledge and skills tests required
- X — Combination of N and H — tank vehicle carrying hazardous materials
CDL Requirements — Who Qualifies
- Must be at least 18 years old for intrastate (within one state) driving
- Must be at least 21 years old for interstate (crossing state lines) driving
- Must hold a valid regular driver's license
- Must pass a DOT physical medical examination
- Must not have certain disqualifying offenses on your record
- Must be legally authorized to work in the United States
DOT Medical Certificate Requirements
All CDL holders must pass a DOT physical exam performed by a certified medical examiner on the FMCSA National Registry. The exam checks:
- Vision — at least 20/40 in each eye with or without correction
- Hearing — must perceive a forced whispered voice at 5 feet
- Blood pressure — must be below 180/110 without disqualifying conditions
- No insulin-dependent diabetes (unless granted exemption)
- No epilepsy or seizure disorders
- No use of Schedule I drugs
Medical certificates are valid for up to 2 years. Drivers with certain conditions may receive shorter validity periods.
CDL Testing Process
Getting your CDL involves three steps:
- Step 1 — Commercial Learner's Permit (CLP) — pass knowledge tests at your state DMV. Hold CLP for minimum 14 days before skills test
- Step 2 — Entry-Level Driver Training (ELDT) — complete training at an FMCSA-registered training provider. Required since February 2022
- Step 3 — CDL Skills Test — three-part test: pre-trip inspection, basic vehicle control, and on-road driving
CDL Disqualifying Offenses
The following will result in CDL disqualification:
- Driving under the influence of alcohol (BAC 0.04% or higher for CDL holders)
- Refusal to take an alcohol or drug test
- Leaving the scene of an accident
- Using a CMV to commit a felony
- Two or more serious traffic violations within 3 years
CDL Renewal
CDLs must be renewed every 4-8 years depending on the state. At renewal you must pass a vision test and medical exam. No skills test is required at renewal unless your CDL has been expired for more than one year.
Tracking CDL Expiry With TruxlyOS
TruxlyOS compliance dashboard tracks every driver's CDL expiry date and DOT medical card expiry. Automatic email alerts are sent to fleet managers 30, 14, 7, and 1 day before expiry — so you never have a driver go out of compliance without warning.
