The class b permit test is the set of written knowledge tests you pass to get a commercial learner's permit (CLP) for a Class B vehicle, such as a straight truck, dump truck, box truck or large bus. For most people that means the general knowledge test plus the air brakes test, and federal rules require a score of at least 80 percent on each knowledge test (49 CFR 383.135, published at ecfr.gov).
Quick answer
A CDL B permit lets you practice driving a heavy single vehicle on public roads with a qualified CDL holder beside you. You get it from your state licensing agency after you pass the knowledge tests, show a medical certificate and prove your identity. You then hold it at least 14 days, finish entry-level driver training, and take a three-part skills test for the Class B CDL.
What is a CDL B permit?
Under the Federal Motor Carrier Safety Administration (FMCSA) rules, Class B means any single vehicle rated at 26,001 pounds or more, or such a vehicle towing a trailer rated at 10,000 pounds or less (49 CFR 383.91). The permit is the CLP for that class. It is not a license to drive alone: the federal rule says a CLP holder must always be accompanied by a valid CDL holder with the right class and endorsements, seated next to you (or, on a bus, directly behind you or in the first row).
A CLP can carry only three endorsements: passenger (P), school bus (S) and tank (N). With P or S you cannot carry passengers other than examiners, trainers and other trainees, and with N you can drive only an empty, purged tank. Hazmat is never allowed on a CLP.
Step-by-step: from class b permit test to CDL
- Check the class b permit requirementsYou need a valid regular driver license from the same state, and you must be at least 18. To drive across state lines or haul hazmat you must be 21.
- Get a DOT medical examMost drivers need a medical examiner's certificate from an examiner on the FMCSA National Registry. You also self-certify the type of driving you will do.
- Pass the knowledge testsGeneral knowledge first, then air brakes and any endorsement tests you need, such as passenger or tank.
- Hold the CLP and trainFederal rules require entry-level driver training (ELDT) from a provider on the FMCSA Training Provider Registry before your first Class B skills test, and you must hold the CLP at least 14 days.
- Pass the skills testPre-trip vehicle inspection, basic control skills (backing and maneuvers) and a road test, in a vehicle that matches the class you want.
Which knowledge tests you need for Class B
- General knowledge: required for everyone, in every class.
- Air brakes: needed if you will drive a vehicle with air brakes, which most Class B trucks and buses have. Skip it and your CDL carries an air brake restriction.
- Passenger (P): for buses designed to carry 16 or more people, including the driver.
- School bus (S): needs the passenger endorsement too.
- Tank (N): for liquid or gas tanks of the size the rules cover.
- Hazmat (H): a knowledge test plus a TSA security threat assessment. You must finish ELDT for hazmat before this knowledge test.
- Combination vehicles: not needed for Class B. That test belongs to Class A.
Class A CDL vs Class B
Class A covers combinations where the towed vehicle is rated over 10,000 pounds, such as a tractor-trailer. Class B covers single heavy vehicles. A Class A CDL also lets you drive Class B and C vehicles if you hold the right endorsements, but a Class B CDL does not let you pull a heavy trailer. If you think you may want tractor-trailer work later, compare both before you pay for training, because upgrading from B to A means another round of ELDT and a new skills test.
Class b permit test cost and timeline
Fees are set by each state, so check your own agency. Here is what two large states list on their official fee pages in 2026, plus the federal timing rules every state follows.
| Item | Texas (dps.texas.gov) | California (dmv.ca.gov) |
|---|---|---|
| Permit (CLP) | $25, valid 180 days | Included in the commercial application; the CLP is valid 180 days |
| CDL fee | $97 for a new CDL (expires in 8 years) | $100 original Class A or B application, valid 12 months |
| Skills retest | Not listed on the DPS fee page | $46 |
| Minimum wait before skills test | 14 days | 14 days |
| Training (ELDT) | Set by the school | Set by the school; California also requires 15 behind-the-wheel hours |
| Medical exam | Set by the examiner | Set by the examiner |
The fastest path is set by the calendar: at least 14 days on the CLP (Pennsylvania uses 15), plus however long your training takes. Many people need a few weeks to a few months in total, depending on the school's schedule and test appointment waits.
Class b permit test study guide: what to study first
Start with your state's CDL manual, which every agency posts free on its website. The general knowledge and air brakes sections are the core of the class b permit test. In our experience training drivers at US Driving School, air brakes is the section students find hardest, because it is full of numbers and parts they have never seen in a car.
- Read the general knowledge sections on inspection, vehicle control, space management and hazards.
- Take a class b permit practice test after each section and write down every question you miss.
- Move to air brakes. Learn the parts in the order the air travels, then memorize the pressure numbers.
- Add endorsement sections only after general knowledge and air brakes are solid.
- Finish with mixed practice tests until you score well above 80 percent every time.
Test questions often reward the safest choice. When two answers look right, pick the one that slows down, adds space or stops the vehicle.
FAQ
What is a CDL B permit?
It is a commercial learner's permit for Class B vehicles: single vehicles rated 26,001 pounds or more. It lets you practice on public roads only with a qualified CDL holder beside you.
What are the class b permit requirements?
A valid regular driver license from your state, age 18 or older (21 for interstate or hazmat), a medical examiner's certificate for most drivers, identity documents, and passing scores on the knowledge tests.
How much does the class b permit test cost?
It depends on the state. Texas lists $25 for the CLP. California lists $100 for an original Class A or B application. Check your own agency's fee page.
How many questions can I miss?
Federal rules require at least 80 percent on each knowledge test. The number of questions varies by state, so ask your agency or check its CDL manual.
Do I need the combination test for Class B?
No. Combination vehicles is a Class A test. Class B drivers usually take general knowledge and air brakes.
Rules and fees change, so confirm each step with your state licensing agency and FMCSA (fmcsa.dot.gov) before you apply. DMVZone is a study resource, not a government agency.
