What's on the CDL permit (CLP) test: Class A vs B, endorsements and the federal rules

The CDL permit test is not one test. Everyone takes the general knowledge test; the rest depends on the class of vehicle you want and the endorsements you add. The pass mark is federal: at least 80 percent on each test. The number of questions is not; each state builds its own tests from a federally approved question pool. Here is what 49 CFR Part 383 and the national CDL manual say, so you know which tests to study for. Practice each one at /cdl/.

What a CLP is

A commercial learner's permit (CLP) lets you drive a commercial motor vehicle (CMV) for behind-the-wheel training with a qualified CDL holder beside you. Under 49 CFR 383.25 it only counts as a valid CDL for training when:

• A driver with a valid CDL of the right class and endorsements rides with you the whole time, in the front seat (or, in a bus, directly behind you or in the first row).
• You hold a regular license from the same state that issued the CLP.
• You have passed the general knowledge test for the type of CMV you plan to drive.
• You are at least 18.
• You are not hauling hazardous materials.

The CLP is a separate document from your license and your CDL. You cannot get a first CDL without holding one, and you cannot take the CDL skills test in the first 14 days after it is issued.

How long a CLP is valid

Federal law caps a CLP at one year from the date it was first issued. A state may issue it for less and renew it, but never past that one-year mark; after that you retake the general and endorsement knowledge tests. California, for example, issues its CLP for a maximum of 180 days with one 180-day renewal, as long as the expiration stays within a year of the first application. Oregon adds another clock: knowledge test results there are valid for six months, so the CLP application must be finished in that window.

The three CDL classes

Your class decides which knowledge tests you take. 49 CFR 383.91 defines three vehicle groups:

A driver who has passed the Class A knowledge and skills tests may also drive Class B and C vehicles, and a Class B driver may drive Class C, provided they hold the needed endorsements.

Which knowledge tests each class needs

The national CDL manual says you take one or more knowledge tests depending on your class and endorsements. The pieces are:

• General knowledge (everyone). 49 CFR 383.111 lists 20 areas every CMV driver must know, from inspection, shifting and backing to speed and space management, night driving, skid control, cargo and fatigue. Practice at /cdl/general-knowledge/.
• Air brakes (if your vehicle has air brakes, including air-over-hydraulic). Seven more areas, such as low air pressure, a contaminated air supply and inspecting the system. Practice at /cdl/air-brakes/.
• Combination vehicles (Class A). Three more: coupling and uncoupling, inspecting a combination, and operating it safely, including its air brakes. Practice at /cdl/combination-vehicles/.

So a Class A permit normally means general knowledge plus combination vehicles, and air brakes because tractor-trailers use them. Fail the combination test and the state must not issue a Class A CLP or CDL at all. A Class B permit means general knowledge, plus air brakes if the truck or bus has them. Class C is general knowledge plus the endorsement that makes the vehicle a CMV, usually passenger or hazmat. Oregon's DMV page puts it the same way: the combination test is for Class A permit applicants only, and the air-brake test is for air-brake-equipped vehicles only.

Endorsements that add a knowledge test

Endorsements are letters on a CLP or CDL that allow certain vehicles or cargo. 49 CFR 383.93 sets the test for each:

The X code is not a separate test; it appears when you hold both tank and hazmat, meaning you passed both knowledge tests. A tank vehicle here means a tank or tanks with an individual capacity over 119 gallons and a total of 1,000 gallons or more. Hazmat also requires a TSA background check with fingerprints. States may add endorsements of their own beyond the federal six.

Endorsements a CLP can carry

Only passenger (P), school bus (S) and tank (N) may go on a CLP, and you pass that endorsement's knowledge test when you apply. Each brings a restriction on the permit: with P or S you may carry no passengers other than examiners, inspectors, other trainees and your supervising CDL holder; with N you may drive only an empty tank that never held unpurged hazmat. Hazmat and doubles/triples are earned on the CDL itself.

The 80 percent rule and the air-brake restriction

49 CFR 383.135 sets the passing score: at least 80 percent correct on each knowledge test, in every state.

The same rules create the best-known CDL restriction. If you do not take or fail the air-brake knowledge test (or take the skills test in a vehicle without air brakes) and the state still issues your CLP or CDL, it must carry code L, "No Air brake equipped CMV". That bars you from any CMV with any type of air brakes, which rules out most tractor-trailers and large buses. To remove it you take a modified skills test, perform the air-brake pre-trip inspection and pass the air-brake knowledge test. The manual lists ten standardized restriction codes in all; others, like E (no manual transmission) and O (no tractor-trailer), come from the vehicle you use on the skills test.

What is federal and what your state decides

49 CFR 383.133 tells states how to build knowledge tests, which is why question counts differ:

• Questions come from the FMCSA pre-approved pool for each vehicle group and endorsement.
• Each test has a set number of questions, with a prescribed number from each knowledge area, but the regulation does not say what that number is. It sits in the state's FMCSA-approved test-generation method.
• A quarter of the questions on each new version must be new, and repeated questions move position with their three answer choices reordered.
• If you fail, you get a different version on the retake.
• Tests may be written, oral or computer-based, and may be given in a foreign language if no interpreter is used. States can be stricter: Oregon offers its general knowledge test in English only.

So do not trust a single question count you read online. The California, Oregon and Nevada CDL pages we checked publish no count at all; your state's CDL manual or testing page is where to confirm it. The national manual's "What Sections Should You Study" table (Section 1, Figure 1.2) maps manual sections to each class and endorsement.

The skills test, by contrast, is standardized: vehicle inspection, basic control, then on-road driving, in that order, passing each before the next. Interpreters are not allowed and instructions are in English.

Entry-level driver training (ELDT)

Since February 7, 2022, 49 CFR Part 380 Subpart F requires training from a provider on FMCSA's Training Provider Registry if you are getting a Class A or B CDL for the first time, upgrading from B to A, or adding a passenger, school bus or hazmat endorsement for the first time.

Timing matters for permit planning. ELDT must be done before the Class A or B skills test, before the P or S skills test, and before the H knowledge test. The rule does not list the general knowledge test, so you can earn your CLP first and train while you practice on it. Theory and behind-the-wheel training must be finished within one year of starting. Drivers who already held the CDL or endorsement before February 7, 2022 are exempt for that credential. States can add more: California requires at least 15 hours of behind-the-wheel training, with proof on its own form, before it issues the CDL.

Sources

• 49 CFR 383.5 Definitions
• 49 CFR 383.25 Commercial learner's permit (CLP)
• 49 CFR 383.71 Driver application and certification procedures
• 49 CFR 383.91 Commercial motor vehicle groups
• 49 CFR 383.93 Endorsements
• 49 CFR 383.95 Restrictions
• 49 CFR 383.111 Required knowledge
• 49 CFR 383.133 Test methods
• 49 CFR 383.135 Passing knowledge and skills tests
• 49 CFR 383.153 Information on the CLP and CDL documents
• 49 CFR 380.600 ELDT compliance date
• 49 CFR 380.603 ELDT applicability
• 49 CFR 380.609 General entry-level driver training requirements
• National CDL Manual, 2005 CDL Testing System, Section 1 (AAMVA; Iowa DOT edition)
• California DMV: Commercial Driver's Licenses (CDL)
• Oregon DMV: Getting a Commercial Driver License or Commercial Learner Permit
• Nevada DMV: Commercial Driver License