Quick answer: Maryland uses the six federal CDL endorsements — T (doubles/triples), P (passenger), S (school bus), N (tank), H (hazardous materials), and X (tank plus hazmat). Every one requires a knowledge test; P and S also require a road skills test, and H and X require a TSA security threat assessment with fingerprints. Restriction codes such as L (no air brakes), E (no manual transmission), and Z (no full air brakes) limit what you can drive. Your endorsements also change how hard a traffic ticket hits — an H or X endorsement can turn a one-year disqualification into three years.
I’m David Waranch, and I’ve represented Maryland truck drivers and commercial drivers for years. Below is what each endorsement covers and requires — and then the part that matters most in my office: how those letters on your license change what a citation actually costs you.
What Are Maryland’s CDL Endorsements?
Maryland follows the federal endorsement coding in 49 C.F.R. § 383.93. An endorsement is added to your commercial license after you pass the required test for a specific type of vehicle or cargo. Here are all six and what each one takes.
| Code | What it covers | What it requires |
|---|---|---|
| T | Double and triple trailers | Knowledge test |
| P | Passenger vehicles designed for 16 or more people, including the driver | Knowledge test + road skills test |
| S | School buses | P endorsement first, then a school-bus knowledge test, skills test, and background check |
| N | Tank vehicles (individual tank over 119 gallons; 1,000 gallons or more aggregate) | Knowledge test |
| H | Placarded hazardous materials (non-tank) | Knowledge test + TSA security threat assessment (fingerprints, background check) |
| X | Tank vehicle carrying hazardous materials (combined N + H) | Knowledge test + TSA security threat assessment |
One detail I see stated wrong constantly, including on other lawyers’ sites: the passenger threshold is 16 or more including the driver — so fifteen passengers plus you. It is not “over 16.” Get that wrong and you’re operating without the endorsement your vehicle requires, which is its own countable violation. Only P, S, and N can appear on a commercial learner’s permit; hazmat endorsements require you to be 21 and to clear the federal security check first.
What Does Each Endorsement Actually Require?
T (doubles/triples) and N (tank) are knowledge-test-only. You study the relevant section of the CDL manual and pass the written exam — no separate road test. N is required once a tank’s individual rated capacity tops 119 gallons, or the aggregate rated capacity reaches 1,000 gallons or more.
P (passenger) takes both a knowledge test and a behind-the-wheel skills test in a representative passenger vehicle. S (school bus) is the most involved: you first meet the P passenger requirements, then pass a school-bus-specific knowledge test and skills test, and clear a background check. School bus drivers carry children, and the state screens accordingly.
H (hazmat) and X (tank + hazmat) add a step none of the others have: a Transportation Security Administration security threat assessment. You submit fingerprints, TSA runs a criminal, immigration, and terrorism-database check, and only then can the state issue or renew the endorsement. X simply combines the tank and hazmat authority in one code, so it carries the hazmat vetting too.
What Do the CDL Restriction Codes Mean?
Restrictions are the opposite of endorsements: instead of adding authority, they take it away, usually because of the vehicle you tested in or a medical status. The common federal codes appear on the front of your license.
| Code | Restriction |
|---|---|
| L | No air brakes — you tested in a vehicle without a full air-brake system |
| Z | No full air brakes — you tested in a vehicle with air-over-hydraulic brakes |
| E | No manual transmission — you tested in an automatic |
| O | No tractor-trailer (no Class A fifth-wheel connection) |
| M | No Class A passenger vehicle (P or S limited to Class B) |
| N | No Class A or B passenger vehicle |
| K | Intrastate only — you cannot drive across state lines |
| V | Medical variance documentation is on file |
These matter more than drivers assume. If you carry an L or E restriction and drive a rig it forbids, you are again operating outside your license class — the same kind of countable violation as missing an endorsement. To clear a restriction, you retest in a vehicle that meets the full standard. If you’re still working out which endorsements and class you need in the first place, my guide to getting a Maryland CDL walks through the process.
Why Does the Hazmat (H/X) Endorsement Take So Long?
Because it is the only endorsement gated by a federal security clearance, not just a test. Under 49 C.F.R. Part 1572, the TSA security threat assessment reviews your criminal history, immigration status, and mental-capacity records, and certain convictions permanently or temporarily disqualify you from holding the endorsement. It is not a one-time hurdle, either: the assessment must be renewed, and the renewal period does not exceed five years. So an H or X endorsement means a fresh background check every renewal cycle for as long as you hold it — plan the fingerprint appointment and processing time well before your card expires.
How Do Your Endorsements Change What a Ticket Costs?
This is the part the licensing guides skip. Your endorsements don’t just decide what you can drive — they change how badly a single conviction hurts.
Under 49 C.F.R. § 383.51, mirrored in Maryland by Md. Code, Transp. § 16-812, a major offense — DUI, refusing the test, or a BAC of 0.04 or more in a commercial vehicle — normally disqualifies you for one year. Commit that same offense while operating a CMV that is transporting placarded hazardous materials, and the disqualification is three years. Same conduct, same BAC, triple the penalty, purely because of what was on your trailer. A second major offense — in any vehicle, at any time — is a lifetime disqualification.
And driving without the right endorsement is itself a serious traffic violation under the federal table. On its own it carries no disqualification, but a second serious violation within three years is a 60-day disqualification and a third is 120 days — and that missing endorsement stacks with your speeding and lane-change tickets toward the same count. Railroad-grade-crossing violations, which tank and hazmat drivers hit constantly because they’re required to stop, carry a minimum 60-day disqualification on the first conviction. There is no free one. For the full ladder, see my page on CDL disqualifications in Maryland and how traffic tickets affect a Maryland CDL.
A PBJ will not save your CDL. Probation before judgment spares most Maryland drivers a conviction and points, but the federal anti-masking rule in 49 C.F.R. § 384.226 forbids a state from hiding a CDL holder’s conviction. Maryland cannot mask it, whatever a judge might allow. So never just pay a commercial ticket — paying is a guilty plea, and for a CDL holder a guilty plea is a conviction that counts toward disqualification and follows you to every carrier you ever apply to. These cases have to be won on the merits.
Do I Need Entry-Level Driver Training First?
For some endorsements, yes. Since February 2022, federal Entry-Level Driver Training (ELDT) rules apply. If you are seeking an S, P, or H endorsement for the first time, you must complete training with a provider listed on the FMCSA Training Provider Registry before you’re allowed to take the test. This trips people up because most of the CDL guidance floating around online predates the rule — if you trained with someone who isn’t on the registry, the test result doesn’t count. If a ticket has already put your endorsements at risk, talk to a Maryland truck driver traffic violation lawyer before you do anything else, and read the full Maryland CDL and commercial driver guide.
Sixteen or more, counting the driver. If the vehicle is designed to carry you plus fifteen others, you need the P endorsement. Many sources say over 16, and they are wrong.
Only P and S require a road skills test; T, N, H, and X are knowledge tests only. H and X also require a TSA security threat assessment with fingerprints, and S requires a background check. You must be 21 to hold hazmat.
Yes. The TSA security threat assessment behind an H or X endorsement is not permanent. It must be renewed, and the renewal period does not exceed five years, so you clear a fresh background check each cycle. Start before your card expires.
Law Offices of David R. Waranch — 301-563-9575 · toll-free 1-877-566-2408. Hablamos Español. I represent truck drivers and commercial drivers throughout Maryland.
Last updated: September 2026. Statutory references: 49 C.F.R. §§ 383.51, 383.93, 383.95, 384.226, Part 1572; Md. Code, Transp. § 16-812. This page is general information about Maryland and federal law, not legal advice, and reading it does not create an attorney-client relationship.