The F Endorsement Lets You Haul Hazardous Materials in a Tank Truck

An F endorsement on a Tennessee commercial driver's license authorizes you to operate a tank truck carrying hazardous materials. The "F" stands for tank vehicle — it is separate from the hazmat endorsement (H) that lets you transport hazardous cargo in any vehicle. You need the F endorsement specifically to drive the tank truck itself, regardless of what is inside it.

Tank trucks are different from other commercial vehicles. They have special handling characteristics because the liquid cargo shifts as you brake, accelerate, and turn. The F endorsement requires you to pass a knowledge test that covers tank vehicle operation, weight distribution, and safety procedures unique to these vehicles.

If you want to haul hazardous materials in a tank truck, you will need both the F endorsement and the H (hazmat) endorsement. The F endorsement covers the vehicle type; the H endorsement covers the cargo type. You can get them in either order, but both must appear on your license.

Key Takeaways

  • The F endorsement authorizes you to drive a tank truck, which is defined as any commercial vehicle with a capacity of more than 119 gallons used to transport any liquid or gaseous material.
  • You must pass the Tank Vehicles knowledge test at a Tennessee Driver Services center, which covers braking, acceleration, weight shift, and emergency procedures specific to tank trucks.
  • The F endorsement is separate from the hazmat (H) endorsement; you need both if you plan to haul hazardous materials in a tank truck.
  • Tank truck drivers face unique risks because cargo movement can cause rollover or loss of control, so the test focuses on how to operate safely under these conditions.
  • You must already hold a valid CDL in Tennessee before you can add the F endorsement to your license.

Who Needs the F Endorsement

You need an F endorsement if your job requires you to operate a tank truck. A tank truck is defined as any commercial motor vehicle with a tank or tanks having a capacity of more than 119 gallons used to transport any liquid or gaseous material. This includes fuel tankers, milk tankers, water trucks, and chemical transport vehicles.

If you drive a smaller tank vehicle — one with 119 gallons or less capacity — you do not need the F endorsement. You also do not need it if you drive a regular commercial truck that happens to carry liquids in drums or containers; the endorsement applies only to vehicles with permanently mounted tanks.

Some employers will not hire you as a tank truck driver without the F endorsement already on your license. Others will hire you and give you time to obtain it. Either way, you cannot legally operate a tank truck for commercial purposes without it.

How to Get the F Endorsement in Tennessee

To add an F endorsement to your Tennessee CDL, you must pass the Tank Vehicles knowledge test. You take this test at any Tennessee Driver Services center — the same locations where you obtained your original CDL. You do not need to take a road test for the F endorsement; the knowledge test alone is required.

Before you schedule the test, study the Tank Vehicles section of the Tennessee CDL Manual. This manual is free and available on the Tennessee Department of Safety and Homeland Security website. The test covers tank vehicle characteristics, weight and balance, braking and acceleration, safe driving practices, and emergency procedures.

On test day, bring your current Tennessee CDL and a valid form of identification. The test consists of multiple-choice questions. You must score at least 80 percent to pass. If you do not pass on your first attempt, you can retake the test after waiting one day.

Once you pass, the examiner will issue you an updated CDL with the F endorsement added. There is a fee for the endorsement, which varies and should be confirmed with your local Driver Services center before you arrive.

What the Tank Vehicles Test Covers

The Tank Vehicles knowledge test focuses on the unique handling and safety challenges of operating a tank truck. The test covers how liquid cargo behaves inside a tank — specifically, how it sloshes forward and backward during braking and acceleration, and how it shifts side to side during turns. This movement affects the truck's stability and your ability to control it.

You will be tested on proper braking techniques for tank vehicles, which differ from regular commercial trucks because the cargo weight is concentrated and can cause the vehicle to jackknife or roll. The test also covers acceleration and how to avoid cargo surge when starting from a stop.

Emergency procedures are a major part of the test. You need to know how to respond if your tank truck begins to skid, how to handle a rollover risk, and what to do if cargo begins to leak. The test also includes questions about inspecting a tank truck before operation and recognizing signs of mechanical problems.

Weight and balance questions cover how the tank's location on the chassis affects handling, and how to calculate safe weight distribution when the tank is partially or fully loaded.

Tank Truck Driving Hazards You Should Understand

Tank trucks present hazards that other commercial vehicles do not. The most significant is surge — the forward and backward movement of liquid inside the tank during braking. If you brake too hard, the cargo surges forward, pushing the truck's front end down and lifting the rear wheels, which can cause loss of traction and jackknifing.

Another major hazard is rollover. Tank trucks have a higher center of gravity than flatbed or box trucks because the cargo is concentrated in a tall tank. This makes them more prone to tipping, especially on curves or when making sudden steering corrections. Speed and road conditions matter significantly.

Partially filled tanks are more dangerous than full ones. When a tank is only partly full, the liquid can slosh more freely, creating sudden shifts in weight that are harder to predict and control. Many tank truck accidents happen with partially loaded vehicles.

Tank trucks also present hazards related to their cargo. If you are hauling hazardous materials, you face additional risks of spills, fires, or chemical reactions. Even non-hazardous cargo like milk or water can create problems if it leaks — a wet road surface can cause other vehicles to lose control.

The Difference Between F and H Endorsements

The F endorsement and the H (hazmat) endorsement serve different purposes and are not interchangeable. The F endorsement authorizes you to drive the vehicle type — a tank truck. The H endorsement authorizes you to transport the cargo type — hazardous materials.

You can have an F endorsement without an H endorsement, which means you can drive a tank truck carrying non-hazardous cargo like water, milk, or food-grade liquids. You cannot have an H endorsement without a CDL, but you could theoretically have an H endorsement without an F endorsement — though this is uncommon because most hazmat jobs involve tank trucks.

If you want to haul hazardous materials in a tank truck, you need both endorsements. You will pass two separate knowledge tests: the Tank Vehicles test for the F endorsement and the Hazardous Materials test for the H endorsement. The H endorsement also requires a background check and fingerprinting through the Transportation Security Administration (TSA).

Renewing and Maintaining Your F Endorsement

Your F endorsement renews with your CDL. In Tennessee, a CDL is valid for five years. When you renew your CDL, the F endorsement renews automatically as long as you have not had it suspended or revoked.

You do not need to retake the Tank Vehicles test when you renew your CDL unless Tennessee's CDL Manual has changed significantly or unless you have had your license suspended or revoked. If you let your CDL expire and then reapply, you will need to retake all knowledge tests, including the Tank Vehicles test.

If you receive a traffic violation or safety violation while operating a tank truck, it could affect your CDL status. Serious violations — such as reckless driving, improper lane changes, or following too closely — can result in suspension or disqualification of your CDL and all endorsements.

Frequently Asked Questions

Can I get the F endorsement if I have never driven a tank truck before?

Yes. You do not need prior tank truck experience to obtain the F endorsement. You only need to pass the knowledge test, which covers the theory and safety practices of tank truck operation. Many people pass the test without hands-on experience and then learn to drive the vehicle on the job under supervision.

Do I need the F endorsement to haul water or milk in a tank truck?

Yes. Water and milk are not classified as hazardous materials, so you would not need the H endorsement. However, you still need the F endorsement because you are operating a tank truck. The F endorsement is required for any tank truck operation, regardless of cargo type.

What happens if I drive a tank truck without the F endorsement?

Driving a tank truck without the required F endorsement is a violation of Tennessee commercial driver's license law. You can be cited, fined, and face suspension of your CDL. Your employer can also face penalties for allowing you to operate a vehicle you are not licensed to drive.

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

Once you pass the Tank Vehicles knowledge test, you receive your updated CDL with the F endorsement on the same day at the Driver Services center. You can begin driving a tank truck when ready after you receive the updated license.

Can I take the Tank Vehicles test online?

No. The Tank Vehicles knowledge test must be taken in person at a Tennessee Driver Services center. You cannot take it online or by mail. You must schedule an appointment or visit a center during walk-in hours.