Colorado endorsement codes are letters added to your driver's license that show you're trained and legal to operate specific vehicle types or carry certain cargo

An endorsement code is a single letter — A, H, T, or X — printed on your Colorado driver's license. It tells law enforcement and employers that you've passed the knowledge test and skills test for that endorsement and are legally allowed to drive that class of vehicle or haul that type of cargo. Without the right endorsement, you can be cited even if you're physically capable of operating the vehicle.

Colorado uses the same endorsement system as every other state. The letter appears on the front of your license, and it's tied to your Commercial Driver's License (CDL) class. You can hold multiple endorsements at once — for example, H and X together — if you pass the tests for each one.

Key Takeaways

  • Colorado endorsement codes are A (hazmat), H (passenger), T (double/triple trailers), and X (hazmat and tanker combined), and each requires passing a written knowledge test and a skills test.
  • You must hold a valid CDL class (A, B, or C) before you can add an endorsement; endorsements do not stand alone.
  • The hazmat endorsement (A or X) requires a Transportation Security Administration (TSA) background check and fingerprinting through the Colorado Department of Revenue.
  • You can hold more than one endorsement at the same time if you pass the tests for each one.
  • Endorsement tests are offered at Colorado Department of Revenue driver's license offices; you schedule through their online system or by phone.

The four Colorado endorsement codes and what they allow

A — Hazardous Materials (Hazmat). This endorsement allows you to transport hazardous materials, including explosives, flammable liquids, gases, poisons, and radioactive materials. You must pass a written knowledge test covering hazmat regulations, placarding, and emergency procedures. You also need a TSA background check and fingerprinting; the Colorado Department of Revenue handles this as part of the endorsement process. The hazmat endorsement is valid for five years and must be renewed.

H — Passenger. This endorsement is required to operate any commercial vehicle designed to carry 16 or more passengers, including buses and shuttle vans. You pass a written knowledge test covering passenger safety, loading procedures, and emergency evacuation. There is no skills test for the H endorsement — only the written exam. This endorsement does not require a background check.

T — Double/Triple Trailers. This endorsement allows you to tow double or triple trailers (two or three trailers pulled behind a single tractor). You must pass a written knowledge test covering coupling, uncoupling, and safe operation of multiple trailers. Like the H endorsement, there is no separate skills test — only the written exam. This endorsement is common in Colorado because of freight and agricultural hauling.

X — Hazmat and Tanker Combined. This is a combination endorsement that allows you to transport both hazardous materials and liquids or gases in tanker vehicles. You pass a single written knowledge test that covers both hazmat and tanker regulations. You also need the TSA background check and fingerprinting, just like the A endorsement. The X endorsement is more restrictive than holding A and T separately because it specifically certifies you for tanker hazmat transport.

How to add an endorsement to your Colorado CDL

First, confirm you hold a valid CDL class (A, B, or C). You cannot add an endorsement without an active CDL. If you do not yet have a CDL, you must pass the CDL knowledge test and skills test for your class first.

Next, schedule your endorsement test through the Colorado Department of Revenue. You can book online at dor.colorado.gov or call the driver's license office in your county. Most offices accept walk-ins for endorsement tests, but scheduling ahead reduces wait time. Bring your current Colorado driver's license and proof of residency.

For hazmat endorsements (A or X), you must complete the TSA background check and fingerprinting before or at the same time as your test appointment. The Colorado Department of Revenue will direct you to an approved fingerprinting location. This process takes one to two weeks. You cannot test for hazmat until the background check is submitted.

On test day, you take the written knowledge test at the driver's license office. The test is multiple choice and covers the specific rules and safety procedures for that endorsement. You must score at least 80 percent to pass. If you pass, the endorsement is added to your license when ready, or within one business day if the office needs to reprint your card.

Costs and renewal timelines for Colorado endorsements

The fee for adding an endorsement to your CDL varies by type. As of 2024, most endorsement tests cost between $10 and $20, but fees can change. The Colorado Department of Revenue website lists current fees for each endorsement type.

Hazmat endorsements (A and X) expire after five years and must be renewed. Renewal requires passing the knowledge test again and completing a new TSA background check. Passenger (H) and trailer (T) endorsements do not expire separately — they remain valid as long as your CDL class is valid. When you renew your CDL, your H and T endorsements renew with it.

If your hazmat endorsement expires and you do not renew it, you lose the right to transport hazmat when ready. You cannot legally haul hazmat cargo with an expired A or X endorsement, even if the rest of your CDL is still valid.

When you need multiple endorsements

You can hold A, H, T, and X endorsements at the same time. Many commercial drivers in Colorado hold H and T together because they drive passenger shuttles and also haul trailers. Some hold A and T if they transport hazmat in non-tanker vehicles.

However, you cannot hold both A and X at the same time — they are mutually exclusive because X already includes hazmat authority. If you hold A and want to add tanker authority, you must surrender the A endorsement and test for X instead.

Each endorsement requires its own knowledge test. There is no single "all endorsements" test. If you want H, T, and A, you take three separate written exams on the same day or on different days — your choice.

Endorsement restrictions and disqualifications

Certain criminal convictions and traffic violations can disqualify you from holding a hazmat endorsement. These include felonies involving explosives, hazardous materials, or transportation security; DUI or drug-related convictions; and certain traffic violations committed while operating a commercial vehicle. The TSA background check will flag these issues, and the Colorado Department of Revenue will deny your hazmat endorsement if you have a disqualifying record.

Non-hazmat endorsements (H and T) have fewer restrictions. You must hold a valid CDL class and pass the knowledge test. A suspended or revoked license disqualifies you from all endorsements until your driving privileges are restored.

If you are convicted of a serious traffic violation or lose your CDL, your endorsements are suspended or revoked along with your class. You must retest for each endorsement when your CDL is restored.

How endorsements affect insurance and employment

Commercial auto insurance rates depend partly on your endorsements. Drivers with hazmat endorsements typically pay higher premiums because they transport higher-risk cargo. Passenger endorsements may also increase rates because of the liability exposure of carrying multiple people.

Many employers require specific endorsements as a condition of hire. A school bus driver must have an H endorsement. A tanker truck driver must have an X or A endorsement. A freight hauler pulling doubles must have a T endorsement. Your endorsements directly determine which jobs you can legally perform.

Some employers will hire you and pay for your endorsement tests if you do not yet have them. Others require you to arrive with the endorsement already in hand. Check the job posting or ask the employer before you explore.

Frequently Asked Questions

Can I test for multiple endorsements on the same day?

Yes. You can take the H, T, A, and X knowledge tests on the same day if you schedule them together. Most Colorado driver's license offices can administer multiple tests in one visit. However, if you are testing for hazmat (A or X), your TSA background check must be completed first, which can take one to two weeks.

What happens if I fail an endorsement test?

You can retake the test. There is no waiting period between attempts in Colorado, though some offices may ask you to schedule a new appointment. You pay the test fee again for each attempt. Most people pass on the second try if they study the Colorado CDL manual.

Do I need a skills test for any endorsement?

No. Colorado requires only a written knowledge test for all endorsements. The H, T, A, and X endorsements do not include a separate driving skills test. Your CDL class (A, B, or C) required a skills test when you first obtained it, but endorsements do not.

Can I add an endorsement if my CDL is suspended?

No. Your CDL must be valid and active. If your license is suspended, revoked, or expired, you cannot test for or add an endorsement. You must restore your driving privileges first.

How long does it take to get a hazmat endorsement after I pass the test?

If you pass the knowledge test and your TSA background check clears, the endorsement is added to your license the same day or within one business day. The longest part is the background check itself, which takes one to two weeks before you can even test. Plan for three to four weeks total from start to finish.