Think of your CDL as a base license and endorsements as add-ons that unlock specific types of driving jobs. Without endorsements, your CDL lets you haul general dry freight in a standard trailer. Add endorsements and you can carry hazardous materials, drive tankers, operate buses, or pull doubles and triples. Each endorsement requires passing an additional knowledge test — and some require a skills test or background check. Here's what each one involves.
HazMat (H) Endorsement
The Hazardous Materials endorsement is the most valuable from a pay standpoint. HazMat drivers typically earn $5,000 to $10,000 more per year because the freight pays a premium and fewer drivers carry the endorsement. You'll need to pass a HazMat knowledge test and a TSA security threat assessment that includes fingerprinting and a background check. The TSA check costs about $87 and takes several weeks to process, so start early. In Washington, you can take the HazMat knowledge test at any DOL office.
Tanker (N) and Tanker-HazMat (X) Endorsements
The Tanker endorsement lets you drive tank vehicles that carry liquid or gaseous cargo. Driving a tanker is genuinely different from pulling a dry van — the liquid surge during braking and turning changes how the vehicle handles. If you want to haul both hazardous and liquid cargo, you need the combination X endorsement, which covers both. Fuel delivery, chemical transport, and milk hauling all require at least a Tanker endorsement. The test covers surge, baffles, bulkheads, and loading/unloading procedures.
Doubles/Triples (T) Endorsement
This endorsement authorizes you to pull double or triple trailers. It's particularly valuable in the Pacific Northwest because carriers like UPS and FedEx run doubles on I-5 between Portland, Seattle, and points north. The knowledge test covers coupling and uncoupling multiple trailers, handling characteristics, and inspection procedures specific to multi-trailer combinations. No additional skills test is required — just the written exam.
Passenger (P) and School Bus (S) Endorsements
The Passenger endorsement lets you drive vehicles designed to carry 16 or more passengers, including buses. If you specifically want to drive a school bus, you need both the P and S endorsements plus an additional skills test in an actual school bus. School bus drivers in Washington state also need to pass a separate background check. These endorsements are typically pursued by people targeting transit agency jobs, charter bus companies, or school districts rather than freight carriers.
Which Endorsements Should You Get First?
If you're going into freight hauling, start with your base CDL and add HazMat and Tanker within your first year. Those two endorsements open the most doors and have the biggest impact on your pay. Doubles/Triples is worth adding if you're targeting LTL carriers in the Puget Sound area. At National Standard Trucking School, we help students understand which endorsements match their career goals during training. We don't just teach you to pass the CDL test — we help you plan for what comes after. Call (253) 210-0505 to talk through your options.
