A Complete Guide to CDL Restriction Codes

As a commercial truck driver, your Commercial Driver’s License (CDL) includes a set of codes that indicate your endorsements and restrictions. These CDL restriction codes define what types of vehicles you can drive, which equipment you can use, and any limitations on your driving privileges. Understanding these codes is crucial to ensure compliance with FMCSA regulations and avoid costly violations.

In the following sections, we’ll explain the most common CDL restrictions, how they impact your driving rights, and the steps you can take to remove them if you’re eligible.

What are CDL restrictions?

A CDL restriction is a limitation applied to a driver’s Commercial Driver’s License, defining what types of vehicles they can operate and under what conditions. While CDL endorsements expand your driving privileges by allowing you to operate additional types of Commercial Motor Vehicles (CMVs), restrictions place boundaries on your license.

In other words, CDL license restrictions outline the specific limitations placed on the driving privileges. On the driver’s license, these restriction codes appear on the front—located beneath the “Expiration Date” and “E” Endorsement fields, following the letter “R.” The full explanation of each restriction is printed on the back of the CDL license, providing details about what conditions or limitations apply to the driving privileges.

These CDL restrictions are designed to enhance road safety by ensuring drivers operate only the vehicles they are properly trained and qualified to handle. For instance, a driver who has not passed the air brake test will be restricted from operating vehicles equipped with air brakes.

Types of CDL license restrictions

Eight primary restrictions can be placed on a CDL. While having restrictions on your license is legal, it can limit the range of jobs and driving opportunities available to you. The good news is that most CDL restrictions can be removed. 

Keep in mind that this is not an exhaustive list, as individual states may impose additional restrictions. Always check your state’s CDL regulations to ensure your license remains compliant.

This list covers the most common CDL restrictions, but it may not include every restriction used nationwide. Each state can have its own set of restriction codes or use different letters to represent them. It’s important to check your specific state’s CDL regulations to understand all applicable restrictions and ensure you remain fully compliant.

Understanding CDL restriction codes

‘E’ restriction code on CDL – No manual transmission-equipped CMV

The E restriction on a Commercial Driver’s License (CDL) indicates that the driver is not authorized to operate a commercial motor vehicle (CMV) with a manual transmission. This restriction is applied when a driver completes the CDL skills test in a vehicle equipped with an automatic or semi-automatic transmission.

With an E restriction, the driver can operate only CMVs with automatic transmissions. While this may not be an issue for drivers whose employers use automatic trucks, it can limit job opportunities at carriers that primarily use manual transmission vehicles, especially in traditional long-haul trucking.

How does the E restriction work?

The E restriction is added to a CDL if the driver:

• Takes the skills test in a vehicle with an automatic transmission.
• Has not demonstrated proficiency in operating a CMV with a manual transmission.

Essentially, the restriction ensures that drivers are properly tested and experienced in the type of transmission they are licensed to operate.

How to remove the E restriction?

To remove the E restriction, a driver must:

• Obtain a Commercial Learner’s Permit (CLP) without the restriction and hold it for at least 14 days.
• Pass the on-road skills test in a CMV equipped with a manual transmission.
• Obtain a new CDL reflecting the removal of the E restriction. Standard licensing fees apply.

Once completed, the driver can legally operate both manual and automatic transmission CMVs, broadening their range of eligible vehicles and employment opportunities.

‘K’ restriction code on CDL – Intrastate only

The K restriction on a Commercial Driver’s License (CDL) limits a driver to operating commercially within the state where the CDL was issued. Drivers with this restriction cannot transport freight across state lines. The restriction is primarily applied to:

• Drivers under 21 years old, who are not legally allowed to operate a commercial motor vehicle (CMV) in interstate commerce.
• Drivers with certain medical conditions that prevent them from meeting federal standards for interstate driving, but who may qualify for intrastate operation under a medical waiver.

How does the K restriction work?

The K restriction is applied when:

• The driver fails the interstate commerce portion of the written CDL test.
• Federal or state regulations limit the driver to intrastate operations due to age or medical conditions.

With this restriction, the driver can legally operate CMVs only within the state of CDL issuance. Loads must start and end within the same state, and the driver is ineligible for most regional or long-haul interstate jobs. However, intrastate driving opportunities, such as local deliveries or short-haul freight, remain available.

How to remove the K restriction?

To remove the K restriction, a driver must:

• Reach the age of 21, or meet federal medical standards for interstate driving.
• Visit the local DMV office to upgrade their CDL and remove the restriction.

Once removed, the driver is authorized to operate CMVs across state lines, opening access to regional and long-haul driving opportunities.

‘L’ restriction code on CDL – No air brake-equipped CMV

An L restriction on a Commercial Driver’s License (CDL) indicates that the driver is not authorized to operate a commercial motor vehicle (CMV) equipped with air brakes. This restriction prevents the driver from operating vehicles with full air brake systems, including most semi-trucks and other large commercial vehicles. Since most CMVs over 26,000 pounds rely on air brakes, an L restriction can significantly limit employment opportunities for those pursuing a Class A or Class B CDL.

How does the L restriction work?

The L restriction is applied if a driver has not:

• Passed the Air Brakes Knowledge Test.
• Correctly identified the components of an air brake system.
• Properly performed an air brake system inspection.
• Completed the Skills Test in a vehicle equipped with a full air brake system.

In other words, the restriction is added if a driver takes the CDL skills test in a vehicle without air brakes or fails the air brakes portion of the written or skills test.

How to remove the L restriction?

To remove the L restriction and gain authorization to operate vehicles with air brakes, a driver must complete the following steps:

• Hold a Commercial Learner’s Permit (CLP) without the restriction for at least 14 days.
• Pass the air brakes knowledge test, if not already completed.
• Complete the skills test in a vehicle equipped with air brakes, including both the vehicle inspection and on-road driving portions.
• Obtain a new CDL with the L restriction removed. Standard licensing fees apply.

The L restriction ensures that drivers are properly trained and tested on air brake systems before operating CMVs that rely on them. The good news is that the air brakes test can be retaken as many times as necessary until the restriction is lifted.

‘M’ restriction code on CDL – No class A passenger vehicle

The M restriction on a Commercial Driver’s License (CDL) limits a driver’s ability to operate Class A passenger vehicles, such as large buses. This restriction typically occurs when a driver holds a Class A CDL but completed the “P” (passenger) or “S” (school bus) endorsement skills test in a Class B or C passenger vehicle.

With an M restriction, a driver can operate all Class A vehicles that are not passenger vehicles, and can drive Class B or C passenger vehicles (like standard buses), but cannot operate Class A passenger buses, which often include articulated or “bendy” buses.

How does the M restriction work?

The M restriction is applied when:

• A Class A CDL holder takes the passenger endorsement test in a Class B or C vehicle instead of a Class A passenger vehicle.
• The driver has not demonstrated proficiency in operating Class A passenger vehicles.

Essentially, the restriction ensures that drivers are properly trained to handle the larger and more complex Class A passenger vehicles before being authorized to operate them.

How to remove the M restriction?

To remove the M restriction, a driver must:

• Obtain a Commercial Learner’s Permit (CLP) without the restriction and hold it for at least 14 days.
• Pass the skills test in a Class A passenger vehicle.

Once these steps are completed, the M restriction is lifted, allowing the driver to operate all Class A passenger vehicles, expanding their range of permitted CMVs and employment opportunities.

‘N’ restriction code on CDL – No Class A or B passenger vehicle

The N restriction on a Commercial Driver’s License (CDL) prevents a driver from operating Class A and Class B passenger vehicles, similar to the M restriction. This restriction typically occurs when a driver holds a Class B CDL but completes their “P” (Passenger) or “S” (School Bus) endorsement in a Class C passenger vehicle.

Drivers with an N restriction are still authorized to operate:

• Non-passenger Class B vehicles
• Class C passenger vehicles

Essentially, this restriction ensures that drivers have the proper training and experience before operating larger passenger vehicles.

How does the N restriction work?

The N restriction is applied when:

• The driver takes the passenger endorsement skills test in a Class C passenger vehicle while holding a Class B CDL.
• The driver has not demonstrated proficiency in operating Class A or Class B passenger vehicles.

With this restriction, the driver cannot legally operate Class A or Class B passenger buses but may still operate Class C passenger vehicles.

How to remove the N restriction?

To remove the N restriction, a driver must:

• Obtain a Commercial Learner’s Permit (CLP) without the restriction and hold it for at least 14 days.
• Pass the skills test in a Class A or Class B passenger vehicle.
• If a Class B passenger vehicle is used, the N restriction will be replaced with an M restriction.
• Obtain a new CDL reflecting the removal or update of the restriction.

Once completed, the driver can legally operate Class A and/or Class B passenger vehicles, expanding the range of vehicles they are authorized to drive and their career opportunities.

‘O’ restriction code on CDL – No tractor-trailer CMV (fifth-wheel connection)

The O restriction on a Commercial Driver’s License (CDL) indicates that the driver is not authorized to operate a tractor-trailer combination vehicle with a fifth-wheel connection. Drivers with this restriction can still operate certain Class A vehicles, such as those equipped with pintle hooks or other non-fifth wheel connections. However, most standard semi-trucks cannot be driven. Since the majority of long-haul commercial trucks use fifth-wheel systems, having an O restriction can significantly limit employment opportunities.

How does the O restriction work?

The O restriction is applied when a driver completes the CDL skills test in a vehicle that does not have a fifth-wheel connection, such as:

• A vehicle equipped with a pintle hook
• A gooseneck hookup
• A ball-and-chain or other non-fifth-wheel connection

This restriction ensures that drivers have not yet demonstrated proficiency in operating tractor-trailer combination vehicles that rely on fifth-wheel systems.

How to remove the O restriction?

To remove the O restriction and gain authorization to operate standard tractor-trailer vehicles, a driver must:

• Obtain a Commercial Learner’s Permit (CLP) without the restriction and hold it for at least 14 days.
• Pass the complete CDL skills test using a vehicle equipped with a fifth-wheel connection.
• Obtain a new CDL reflecting the removal of the O restriction. Standard licensing fees apply.

Removing this restriction opens up a wider range of employment opportunities in traditional trucking and long-haul commercial transportation.

‘P’ restriction code on CDL – No Passengers in a CMV bus

The P restriction on a Commercial Learner’s Permit (CLP) or Commercial Driver’s License (CDL) indicates that the driver is not authorized to operate a commercial bus while carrying passengers. This restriction is typically applied to individuals who hold a passenger (P) endorsement but have not yet completed the full CDL skills test in a passenger-carrying vehicle.

How does the P restriction work?

When a driver is training to earn a passenger endorsement, they are only allowed to operate a commercial motor vehicle (CMV) bus under limited conditions. Under the P restriction, the driver may not transport actual passengers. The only passengers permitted in the vehicle during training are:

• CDL examiners or testers
• State or federal auditors and inspectors
• CDL trainers or supervising drivers
• Other CLP holders participating in training

This restriction ensures that only qualified, fully licensed drivers are responsible for passenger transport, maintaining safety standards during the learning process.

How to remove the P restriction?

To remove the P restriction and gain authorization to carry passengers, the driver must:

• Hold a CLP without the restriction for at least 14 days.
• Pass all required knowledge tests for the vehicle class and passenger endorsement.
• Complete the CDL skills test in a passenger-carrying vehicle of the appropriate class (A, B, or C).

Once these steps are completed, the restriction will be lifted, and the driver will be permitted to legally operate passenger buses under their CDL.

‘V’ restriction code on CDL – CMV medical variance

The V restriction on a Commercial Driver’s License (CDL) indicates that the driver has a medical variance reported to the Federal Motor Carrier Safety Administration (FMCSA). Medical variances are conditions or impairments that could potentially affect a driver’s ability to safely operate a commercial motor vehicle (CMV).

Some of the most common conditions that require a V restriction include: Diabetes, Seizures, Hearing impairments, and Vision impairments.  These variances are documented through the driver’s DOT medical certificate, and the restriction remains on the CDL as long as the medical condition exists.

How does the V restriction work?

Unlike other CDL restrictions, a V restriction does not limit the types of vehicles a driver can operate. Instead, it indicates that the driver must carry documentation verifying the medical variance and maintain compliance with FMCSA requirements. Essentially, it ensures that the driver’s medical condition is officially recognized and monitored while operating a CMV.

How to remove the V restriction?

The V restriction cannot be removed by the state DMV as long as the DOT medical certificate references a medical variance. Drivers must:

• Keep their medical documentation current.
• Follow any FMCSA-approved waivers or requirements for the condition.
• Maintain periodic medical evaluations as required by their medical variance.

By maintaining compliance with FMCSA requirements, drivers with a V restriction can continue to operate commercial vehicles safely, without limiting the class of vehicles they are authorized to drive.

‘X’ restriction code on CDL – No cargo in CMV tank vehicle

The X restriction on a Commercial Driver’s License (CDL) or Commercial Learner’s Permit (CLP) indicates that the driver is not authorized to operate a tank vehicle that contains cargo, liquid, or gas residue. This restriction is commonly applied to drivers who hold an N (Tanker) endorsement but have not yet completed the required skills test in a fully loaded or purged tank vehicle.

How does the X restriction work?

When a driver earns the N endorsement but takes the CDL skills test using an empty tank vehicle, the X restriction is added to their CLP or CDL. This restriction ensures that the driver has not yet demonstrated the ability to safely operate a tank vehicle carrying liquid loads or hazardous materials.

Under this restriction:

• The driver cannot operate any CMV tank vehicle that contains cargo or residue.
• If the tank previously contained hazardous materials, it must be purged and accompanied by a purge certificate before operation.

This restriction helps ensure that drivers gain the necessary training and experience handling the unique challenges of liquid surge and load stability before operating fully loaded tank vehicles.

How to remove the X restriction?

To remove the X restriction and obtain full tanker operation privileges, a driver must:

• Hold a CLP without the restriction for at least 14 days.
• Pass any required knowledge tests for the applicable vehicle class and endorsement.
• Complete the full CDL skills test using a tank vehicle that contains liquid cargo.

Once these steps are completed, the driver will receive a new CDL without the X restriction, authorizing them to operate fully loaded tank vehicles safely and legally.

‘Z’ restriction code on CDL – No full air brake-equipped CMV

A Z restriction on a Commercial Driver’s License (CDL) indicates that the driver is not authorized to operate a commercial motor vehicle (CMV) with a full air brake system. While similar to the L restriction, the key difference is that the Z restriction is applied when a driver completes the CDL skills test in a vehicle with partial air brakes or a hydraulic braking system, rather than failing the air brakes portion of the test.

In other words, if a driver takes the skills test using a vehicle with a combined air-over-hydraulic braking system or a fully hydraulic system, a Z restriction is added to their CDL. This ensures the driver has not yet demonstrated proficiency in operating a vehicle with a full air brake system.

How does the Z restriction work?

A Z restriction is applied when a driver:

• Completes the CDL skills test in a vehicle with partial air brakes or hydraulic brakes.
• Has not demonstrated proficiency in inspecting, operating, or driving a vehicle with a full air brake system.

With this restriction, the driver cannot legally operate semi-trucks or other CMVs that rely entirely on air brakes, which are common in commercial transport.

How to remove the Z restriction?

To remove the Z restriction from a CDL, a driver must:

• Hold a Commercial Learner’s Permit (CLP) without the restriction for at least 14 days.
• Pass any required knowledge tests for air brake-equipped vehicles, if not already completed.
• Complete the skills test in a vehicle with full air brakes, including both the vehicle inspection and on-road driving portions.
• Obtain a new CDL reflecting the removal of the Z restriction. Standard licensing fees apply.

Once these steps are completed, the Z restriction is lifted, allowing the driver to legally operate CMVs with full air brake systems.

Why do CDL restrictions matter?

Understanding and adhering to CDL restrictions is important for several reasons:

1. Employment opportunities:

CDL restrictions can limit the range of jobs available to you. Removing restrictions can expand your career options and demonstrate to employers that you have a broader set of skills, making you a more attractive candidate.

2. Safety:

Restrictions ensure that drivers operate only the vehicles they are trained and qualified to handle. This helps maintain safer roads for everyone.

3. Compliance:

Failing to adhere to CDL restrictions can lead to serious consequences, including fines, penalties, or even license suspension.

Can CDL restrictions be removed?

In most cases, CDL restrictions can be lifted, except when they are related to a permanent medical condition that cannot be resolved. The process for removal varies depending on the restriction: some require passing written knowledge tests, while others may involve completing a training course and successfully passing a skills or driving exam.

Conclusion: Navigating CDL restrictions effectively

Building a successful career as a truck driver starts with understanding your CDL restrictions and knowing which vehicles you are legally authorized to operate. By minimizing restrictions where possible and earning the right endorsements, you increase your job opportunities and position yourself as a skilled, versatile driver. Staying informed about your license, completing the required tests, and maintaining compliance with all regulations ensures that you can confidently pursue your ideal trucking career. In today’s growing trucking industry, proper preparation and knowledge are key to becoming a safe, capable, and highly employable driver.