The tanker endorsement test has 20 questions, and you must answer at least 16 correctly to pass
The tanker (N) endorsement test is a written exam administered by your state's DMV or testing facility. It covers the safe operation and handling of tank vehicles carrying liquids or gases. The test format is consistent across all states: 20 multiple-choice questions, with a passing score of 80 percent (16 correct answers).
You take this test after you have already passed your CDL general knowledge test and any other endorsement tests you need. The tanker test is separate from the air brake test, hazmat test, or any other endorsement you may pursue. Each endorsement requires its own exam.
Testing time is typically 30 to 45 minutes, though the exact window varies by state. You can usually retake the test the same day if you fail, though some states require a waiting period between attempts. Check with your local DMV office for their specific retake policy.
Key Takeaways
- The tanker endorsement test contains exactly 20 multiple-choice questions across all states.
- You need to score 80 percent (16 correct answers) to pass the exam.
- Test time is usually 30 to 45 minutes, depending on your state's procedures.
- You must pass your CDL general knowledge test before taking any endorsement test, including tanker.
- Most states allow you to retake the test the same day if you fail, but confirm this with your DMV office first.
What the tanker test covers
The 20 questions focus on the unique hazards and procedures for hauling liquids and gases in tank vehicles. Topics include surge and slosh (the movement of liquid inside the tank), proper braking techniques, weight distribution, and how to safely load and unload cargo. You will also see questions about inspecting tank vehicles, understanding placards and labels, and responding to spills or leaks.
The test assumes you already know general CDL rules from your general knowledge exam. The tanker questions are specific to tank vehicle operation. You will not be asked about air brakes, hazmat regulations, or passenger transport rules unless you are also taking those endorsements.
Questions are drawn from your state's CDL manual, specifically the tanker section. The exact wording and scenarios can vary, but the topics and difficulty level remain the same across all states.
How to prepare for the tanker test
Your state's CDL manual contains the tanker endorsement section, which is the primary study material. Read through this section carefully, paying attention to surge and slosh dynamics, safe speeds on curves, and proper tank inspection procedures. Most manuals are available free online from your state DMV website.
Practice tests are available through several sources: some state DMV websites offer sample questions, and third-party CDL study sites provide full-length practice exams. Taking a practice test under timed conditions helps you get used to the format and identify weak areas. Aim to score 90 percent or higher on practice tests before you sit for the real exam.
Some drivers take a CDL training course that includes tanker endorsement instruction. These courses are not required, but they can help if you are struggling with the material or prefer classroom instruction. Costs vary widely depending on the provider and whether the course includes behind-the-wheel training.
Testing locations and scheduling
You schedule your tanker test through your state DMV office, either online, by phone, or in person. Some states use third-party testing contractors (often called third-party examiners) to administer CDL tests, while others run all testing through DMV facilities. Your state's website will tell you where to schedule and what documents to bring.
Bring your current driver's license, proof of residency, and any other documents your state requires. Arrive early to allow time for check-in. You will not be allowed to bring study materials, phones, or other devices into the testing room.
Wait times for test appointments vary by location and season. In busy areas, you may need to schedule weeks in advance. Rural areas often have shorter wait times. Plan ahead if you have a important date for obtaining your endorsement.
Passing score and what happens next
A passing score is 16 out of 20 questions correct. Once you pass, your state will add the tanker endorsement (N) to your CDL. This usually happens within a few days, though some states issue it when ready at the testing facility. You will receive an updated license in the mail or can pick it up at your local DMV office.
If you score 15 or lower, you have not passed. You can retake the test, but check your state's rules on waiting periods and retake fees. Some states charge a small fee each time you retake an endorsement test.
Once you have the tanker endorsement, you are legally permitted to operate tank vehicles in your state. However, your employer may have additional training or certification requirements before putting you behind the wheel of a tanker.
Common mistakes on the tanker test
Many test-takers miss questions about surge and slosh because these concepts are specific to tank vehicles and not covered in the general knowledge test. Surge is the forward and backward movement of liquid when you accelerate or brake; slosh is the side-to-side movement when you turn. Understanding how these forces affect braking distance and vehicle stability is critical.
Another frequent error is misunderstanding proper tank inspection procedures. The test expects you to know what to look for before and after each trip: leaks, damage to the tank, proper sealing of valves and caps, and find mounting of the tank to the frame. Skipping or rushing through the inspection section of your manual often costs points.
Some drivers also struggle with questions about weight distribution and how a partially filled tank affects handling differently than a full tank. A half-full tank is often more dangerous than a full or empty tank because the liquid can move more freely inside the container.
State-by-state variations in testing
While the tanker test always has 20 questions and an 80 percent passing score, some states add extra requirements. A few states require you to pass an air brake test before or at the same time as the tanker test if you will be hauling certain types of cargo. Others may require a hazmat endorsement if you are transporting hazardous materials in a tank.
Testing fees also vary by state, ranging from no fee to around $10 to $15 per test. Some states charge a fee only if you retake the test. Check your state DMV website for the exact fee structure.
The content of the test itself is standardized by the Federal Motor Carrier Safety Administration (FMCSA), so the topics and difficulty are the same everywhere. Only the format of delivery and state-specific procedures differ.
Frequently Asked Questions
Can I take the tanker test on the same day as my general knowledge test?
No. You must pass your CDL general knowledge test first, then schedule your tanker endorsement test separately. Some testing facilities allow you to take multiple endorsement tests on the same day if you have already passed general knowledge, but you cannot combine them into one appointment.
What happens if I fail the tanker test?
You can retake it. Most states allow you to retake the test the same day or within a few days, though some have a waiting period of 24 hours or longer. Each retake may have a small fee. There is no limit on how many times you can retake the test, but you must eventually score 16 out of 20 to pass.
Do I need a tanker endorsement to haul any liquid in a tank truck?
Yes, if you are operating a tank vehicle designed to carry liquids or gases, you need the tanker endorsement on your CDL. This applies whether the tank is full, partially full, or empty. If you are hauling hazardous materials in a tank, you will also need a hazmat endorsement in addition to tanker.
How long is the tanker endorsement valid?
Your tanker endorsement is valid for the same period as your CDL. Most CDLs are valid for four or five years, depending on your state and whether you have a medical certificate. When you renew your CDL, you can renew the tanker endorsement at the same time.
Can I study for the tanker test using only online practice tests?
Yes, many drivers pass using only the state CDL manual and online practice tests. However, make sure the practice tests you use are based on your state's manual and cover all the topics in the tanker section. Generic CDL study sites may not match your state's specific test content exactly.