What Is an X Endorsement on a Driver's License?

If you've come across the term X endorsement while researching commercial driver's licenses, you're looking at one of the more specific — and sometimes misunderstood — CDL endorsement codes. Here's what it means, who it applies to, and what shapes whether it matters for a given driver.

CDL Endorsements: A Quick Foundation

A CDL endorsement is an add-on to a commercial driver's license that authorizes a driver to operate a specific type of vehicle or transport a specific type of cargo beyond what the base CDL permits. Common endorsements include H (hazardous materials), T (double/triple trailers), P (passengers), N (tank vehicles), and S (school bus).

Each endorsement typically requires additional testing — a written knowledge exam, a skills test, or both — and some carry federal requirements that apply uniformly across all states.

The X endorsement is different from most because it isn't earned through a separate, standalone test of its own.

What the X Endorsement Actually Means

The X endorsement is a combination endorsement that represents both the N endorsement (tank vehicles) and the H endorsement (hazardous materials) on a single CDL. When a driver qualifies for both N and H separately, many states — following the Federal Motor Carrier Safety Administration (FMCSA) coding system — consolidate them into an X on the license itself.

In plain terms: X = N + H. A driver with an X endorsement is authorized to operate tank vehicles and transport hazardous materials — which often go together in practice, since liquid or gaseous hazmat is frequently transported in tankers.

Some states display the X directly on the license credential in place of the individual N and H codes. Others may show all three. How the endorsement appears on the physical license varies by state.

What It Takes to Get the X Endorsement 🚛

Because the X endorsement combines two separate authorizations, drivers generally need to satisfy the requirements for both the N and H endorsements.

For the N (Tank Vehicle) endorsement, most states require:

• A written knowledge test covering tank vehicle operation, including liquid surge, safe loading, and driving techniques specific to tankers

For the H (Hazardous Materials) endorsement, requirements are more involved and include a federal layer:

• A written knowledge test covering hazmat regulations, placarding, emergency procedures, and proper handling
• A Transportation Security Administration (TSA) security threat assessment, which includes a background check and fingerprinting — this is a federal requirement that applies in every state
• The H endorsement cannot be issued until TSA clearance is complete, regardless of state

Both knowledge tests must typically be passed before the skills portion of CDL testing, and the hazmat background check adds a processing period that varies depending on individual circumstances and application timing.

Key Variables That Affect the Process

While the federal framework sets a baseline, several factors shape how the X endorsement process works in practice:

The TSA security threat assessment is the most consequential variable for many applicants. Certain felony convictions or other disqualifying factors under federal law can make the H — and therefore the X — endorsement unavailable, regardless of state-level driving history.

How the X Endorsement Differs From Other Endorsements ⚠️

Most CDL endorsements are state-administered processes: you study, test, pay a fee, and receive the endorsement. The X endorsement stands apart because the H component involves a federal screening layer that operates independently of any state DMV.

This means the timeline for obtaining an X endorsement is less predictable than, say, adding a T (double/triple trailer) endorsement, which typically requires only a written test. The federal background check introduces a variable outside of state control.

Additionally, because the X endorsement authorizes hazmat transport, drivers holding it are subject to ongoing federal compliance requirements — including regulations governed by the FMCSA and the Department of Transportation — that go beyond what a standard CDL requires.

What Varies by State

States generally follow the federal CDL structure, but the following differ meaningfully:

• Test fees for the N and H knowledge exams
• Renewal requirements and how often the hazmat background check must be repeated
• How the endorsement is displayed on the physical credential
• Whether the state issues the X code explicitly or lists N and H separately
• Scheduling and testing availability for CDL knowledge exams

Some states allow CDL knowledge tests to be taken at third-party testing locations; others require applicants to go through a state DMV office. That distinction affects scheduling timelines significantly.

The Missing Piece

The X endorsement follows a federal framework — but what the process looks like on the ground depends on the state where you're obtaining or holding your CDL, your existing license class, how the TSA background check resolves in your case, and what your employer or intended role actually requires. Those specifics aren't universal, and they're the part that only your state's CDL licensing authority can answer directly.