If you've come across the code "9 06" in the context of a commercial driver's license (CDL), you're likely looking at an endorsement notation — specifically one that indicates a driver is authorized to operate a vehicle requiring air brakes knowledge, or more precisely, that they have removed a restriction related to air brakes. Understanding how CDL endorsements and restrictions work — and how codes like 9 06 fit into that system — helps make sense of what's printed on a commercial license and what it permits.
A CDL endorsement expands what a driver is legally allowed to operate beyond the baseline for their license class. Common endorsements include:
A restriction, by contrast, limits what a driver can operate. Restrictions are often indicated by letter or numeric codes on the physical license.
The "06" restriction code specifically relates to air brakes. Under federal CDL standards, if a driver takes their skills test in a vehicle without air brakes, that restriction is added to their CDL — meaning they cannot legally drive a CMV (commercial motor vehicle) equipped with a full air brake system. Removing that restriction typically requires passing a skills test in an air-brake-equipped vehicle.
The format "9 06" appears in some state licensing systems as a coded entry on a driving record or license document. In this context:
Together, 9 06 typically means the air brake restriction has been removed from a CDL — indicating the driver passed the necessary testing in an air-brake-equipped vehicle and is now cleared to operate those vehicles commercially.
This notation style is not universal. Different states format license codes, endorsement records, and restriction notations differently. Some states use letter codes only; others use numeric or alphanumeric combinations. The 9 06 format is associated with specific state DMV record systems and may not appear identically — or at all — on licenses or records from other states.
Air brakes are standard equipment on most heavy commercial trucks and buses. A CDL holder with an active air brake restriction (sometimes shown as restriction code "L" in federal shorthand) cannot legally drive the vast majority of large CMVs used in commercial transport. That limits:
For most professional drivers operating Class A or Class B vehicles in freight, transit, or passenger transport, having the air brake restriction removed is essentially a prerequisite for full employment eligibility in the field.
To clear the air brake restriction and receive an endorsement or notation like 9 06, a driver generally needs to:
Some states process this automatically when a driver upgrades or retests; others require a separate application or fee. Timelines, fees, and administrative procedures vary by state.
Several factors affect how the air brake restriction is handled and how notations like 9 06 appear on a record:
| Variable | Why It Matters |
|---|---|
| State of licensure | Code formats, fees, and procedures differ by state |
| CDL class (A, B, or C) | Class A testing has different vehicle requirements than Class B |
| Original skills test vehicle | Whether air brakes were present determines if the restriction applies |
| Employer or FMCSA requirements | Federal motor carrier rules may interact with state-level notations |
| Driving record history | Some states may flag prior violations when processing upgrades |
Some states print restriction and endorsement codes directly on the face of the license. Others maintain them only in the driving record database, accessible through an official record request. If you're seeing 9 06 on a printed record rather than the license itself, it may reflect a transaction history entry — a logged event showing when the restriction was removed — rather than a current status field.
Employers running motor vehicle record (MVR) checks will typically see both current endorsements/restrictions and the history of changes. How that history is formatted depends entirely on the state's record system.
The 9 06 endorsement code carries a specific meaning in the states that use it, and the underlying concept — removing an air brake restriction from a CDL — is a federally recognized process. But how it's notated, what testing it required, how it appears on a license versus a driving record, and what fees or steps were involved all trace back to the state where the license was issued. A driver looking to understand what this code means on their specific record, or how to obtain this clearance on their own CDL, is working within a framework set by their state's licensing authority.