CDL Endorsements and Restrictions Explained

Quick answer: Endorsements widen what a CDL may haul or pull: H (hazardous materials), N (tank vehicles), P (passengers), S (school bus), T (double/triple trailers), and X (tank + hazmat combined) — defined in 49 CFR 383.93 with the standardized codes in 383.153. Restrictions narrow it: the federal code table includes E (no manual transmission), K (intrastate only), L (no air-brake CMV), M/N (passenger vehicles only below Class A/B), O (no tractor-trailer), V (medical variance), and Z (no full air brakes), largely driven by the testing rules in 383.95.

Regulatory-change disclaimer: Last reviewed July 17, 2026. Endorsement and restriction requirements are federal; the letters your state prints and how it displays them can vary within the federal code framework. Confirm with FMCSA and your state licensing agency. Not legal advice.

What the two kinds of letters do

A CDL's class sets the vehicle group (Classes A/B/C); the letters adjust it in both directions. Endorsements are earned — each has its own test or check. Restrictions are usually acquired by omission — test in an easier vehicle and the license permanently records what you skipped, until you retest.

Who should read the code tables

Every applicant planning a career lane (the endorsement list IS the job list), and every licensed driver reading the back of a license before a job change — yours or a new hire's.

The six endorsements

• H — hazardous materials. Knowledge test plus a TSA security threat assessment, and first-timers complete the ELDT hazmat theory before the state may test them. H cannot ride on a learner's permit. Drill the material: Hazmat practice test.
• N — tank vehicles. Knowledge test only. Required once you haul liquid or gas in tanks over 119 gallons apiece totaling 1,000+ gallons. Prep: Tanker practice test.
• P — passenger. Knowledge and skills tests in a passenger vehicle; carries sub-restrictions if you test in a smaller bus than your class allows.
• S — school bus. Everything P requires plus the school-bus knowledge and skills tests and the background checks states layer on.
• T — double/triple trailers. Knowledge test only — but pulling doubles safely is its own craft; the test is the floor, not the ceiling.
• X — tank + hazmat combined. One code covering both N and H authorities — the standard combination for fuel haulers.

The restriction codes

From the federal table in 383.153(a)(10) — your state prints these (display conventions can differ slightly):

• E — no manual transmission. Earned by taking the skills test in an automatic.
• K — intrastate only. Usually age- or medical-certification-driven; it fences you inside your state until you qualify for interstate driving and update your self-certification with the licensing agency.
• L — no air-brake CMV. From skipping/failing the air-brakes knowledge test or testing in a vehicle without air brakes. Avoid it: Air Brakes practice test.
• M — Class B/C passenger vehicles only. A Class A holder who took the P skills test in a Class B bus.
• N — Class C passenger vehicles only. Same idea, one class down. (Yes — the letter N does double duty: endorsement N is tank; restriction N is passenger-class.)
• O — no tractor-trailer. From testing in a Class A combination that wasn't a fifth-wheel connection (e.g., pintle hook).
• V — medical variance. Flags that you drive under a federal medical variance — an exemption (hearing or seizure, for example) or a Skill Performance Evaluation certificate — and the paperwork travels with you.
• Z — no full air brakes. From testing in an air-over-hydraulic vehicle.

Why restrictions matter more than they look

Restrictions follow the license, and dispatch reads them. An E restriction quietly removes every manual truck from your job market; an L removes nearly every highway tractor. Clearing one means retesting in the right vehicle — a scheduling and rental problem that costs far more after licensing than avoiding it would have cost during training. Choose the test vehicle deliberately — its equipment list writes itself onto your license.

A realistic example (illustration only)

A student tests in her school's automatic day-cab with full air brakes: no L, no Z — but an E. Six months later the small fleet she wants to join runs 13-speeds. Fixing it takes a retest in a manual — finding one to rent, booking a slot, paying the fee. Her classmate, warned in week one, borrowed a manual for two extra practice days and tested clean. Same school, same money, different map of jobs.

Common mistakes

• Testing in an automatic without deciding you're fine with E forever.
• Assuming T or N requires a road test — both are knowledge-only.
• Trying to add H on a CLP, or skipping the ELDT theory that must precede the hazmat knowledge test.
• Reading restriction N as "tanker" — context matters; on the restriction line it's passenger-class.
• Forgetting K exists — an 18-to-20-year-old's license carries it until the interstate age rule is satisfied.

Endorsement-planning checklist

• Target freight identified → endorsement list written (X for fuel, T for LTL doubles, P/S for buses)
• Knowledge-only vs knowledge+skills separated in the study plan
• TSA check timeline built in if H is on the list
• Test vehicle chosen against the restriction table (manual, full air, fifth wheel)
• State display conventions checked when reading an existing license

Keep learning

• The tests behind the letters: Hazmat · Tanker · Air Brakes · full hub
• Zoom out: the step-by-step guide · CDL Classes Compared
• Build the endorsement plan with us: TLWS Academy · the free on-ramp is CDL Pre-School · email list for new tests and guides.