The tanker endorsement test has 20 questions

The Commercial Driver's License (CDL) tanker endorsement test administered by your state's Department of Motor Vehicles contains 20 multiple-choice questions. You must answer at least 16 of them correctly to pass — that is an 80 percent passing score. The test covers safe handling of tank vehicles, cargo control, and hazard awareness specific to transporting liquids and gases.

Each state administers the same federal test standards, so the number of questions and passing score remain consistent whether you test in California, Texas, or any other state. The test is computer-based in most states, though a few still offer paper versions. Either way, you will see the same 20 questions drawn from the same question bank.

Key Takeaways

  • The tanker endorsement test contains exactly 20 multiple-choice questions, and you need to answer at least 16 correctly to pass.
  • All states use the same federal test standards, so the question count and passing score are identical regardless of where you test.
  • The test focuses on tank vehicle operation, cargo control, and hazmat awareness rather than general CDL knowledge.
  • Most states offer computer-based testing, though you should confirm your state's format when you schedule your appointment.

What topics the 20 questions cover

The tanker endorsement test does not repeat general CDL material you already passed. Instead, the 20 questions focus specifically on the risks and procedures unique to tank vehicles. You will encounter questions about surge and slosh (how liquid moves inside a tank during acceleration and braking), how to load and unload safely, and how weight distribution affects handling.

Other questions address emergency procedures, such as what to do if your brakes fail on a downhill grade while hauling liquid, or how to respond if cargo begins leaking. The test also includes questions about vehicle inspection specific to tanks — checking for leaks, proper sealing, and structural damage. A smaller portion covers hazmat regulations if you are also pursuing a hazmat endorsement alongside tanker.

How long you have to complete the test

Most states allow 30 to 60 minutes to complete the 20-question tanker test, though the actual time most people need is 15 to 25 minutes. The test is not timed in a way that creates pressure; you can work through each question at your own pace. If you finish early, you can review your answers before submitting.

The computer system (or paper form) will show you your score when ready after submission in most states. Some states mail results within a few business days if you test on paper. Either way, you will know whether you passed before you leave the testing location or shortly after.

How the tanker test differs from other CDL endorsement tests

The tanker endorsement test is shorter than some other endorsement tests. The hazmat endorsement test, for example, contains 30 questions. The general CDL knowledge test that all drivers take first is 50 questions. The tanker test's 20-question format reflects that it covers a narrower, more specialized topic — the mechanics and safety of one vehicle type rather than broad driving law or hazmat chemistry.

The tanker test also assumes you already hold a valid CDL. You cannot take the tanker endorsement test without first passing the general CDL written test and the skills test (pre-trip inspection, basic control, and road test). The endorsement test is an add-on that proves you understand tank-specific operation.

Preparing for the 20-question test

Your state's CDL manual contains a tanker section with sample questions and explanations. Reading that section thoroughly is the most direct way to prepare. The sample questions in the manual often mirror the actual test questions closely — sometimes word-for-word — so working through them multiple times builds familiarity with both the content and the question format.

Many people study for 3 to 7 days before taking the tanker test, reviewing the manual for 30 to 60 minutes per day. Since the test is only 20 questions, focused study on the tanker section alone is usually enough. You do not need to re-study general CDL material unless you feel rusty on topics like vehicle inspection or braking systems, which do appear in tanker-specific contexts.

What happens if you do not pass

If you score below 16 correct answers, you do not pass and do not receive the tanker endorsement. Most states allow you to retake the test the same day or within a few days, though some require a waiting period of 24 to 48 hours. You will pay the test fee again for each attempt.

There is no limit to how many times you can retake the test in most states, though a few cap retakes at a certain number per year. Check your state's specific rules when you schedule. Many people pass on the second or third attempt after reviewing the manual more carefully or focusing on the questions they missed.

Frequently Asked Questions

Do I have to pass the tanker test to drive a tank truck?

Yes. If you operate a commercial tank vehicle, you must have the tanker endorsement on your CDL. Driving a tank truck without the endorsement is illegal and can result in fines and license suspension. Some companies will not hire you without it, even if you have general CDL experience.

Can I take the tanker test before I pass the general CDL test?

No. You must hold a valid CDL first. The tanker endorsement is an add-on to an existing CDL, not a standalone credential. You will need to pass the general knowledge test, the pre-trip inspection test, the basic control test, and the road test before you are may be able to access to take the tanker endorsement test.

Are all 20 questions multiple choice?

Yes. Every question on the tanker endorsement test is multiple choice with four answer options. You select one answer per question. There are no fill-in-the-blank, true-or-false, or essay questions on this test.

What score do I need to pass the tanker test?

You need to answer at least 16 out of 20 questions correctly, which equals 80 percent. Scoring 15 or fewer means you did not pass and will need to retake the test. Some states show your score as a percentage; others show the number of questions you answered correctly.

Can I use notes or study materials during the test?

No. The tanker endorsement test is a closed-book exam. You cannot bring your CDL manual, notes, or any reference materials into the testing room. You must answer all 20 questions from memory based on your study beforehand.