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A vs B vs C contractor licenses: which do you need?

By Contractor Lookout · Updated November 3, 2026

For a single-trade job such as electrical, plumbing or roofing, look for the C specialty license for that trade. For a project that combines several unrelated trades, such as a remodel or an accessory dwelling unit, a B General Building contractor is the usual choice.

California sorts contractor licenses into three main groups, A, B and C, plus two certifications that sit on top of a license. A license covers only the classifications printed on it, so the letter matters.

The groups at a glance

License Name When it fits
A General Engineering Its own scope, defined by CSLB. Check CSLB’s classification page
B General Building Projects involving at least two unrelated trades other than framing or carpentry
B-2 Residential Remodeling Residential remodels. Check CSLB’s classification page for the exact limits
C classes Specialty trades One trade, such as electrical, plumbing or roofing
C-61 Limited Specialty Narrow trades, each tied to a D subcategory
ASB Asbestos certification Asbestos work of 100 sq ft or more, on certain licenses
HAZ Hazardous substance removal certification Hazardous site cleanup and underground tank work

In CSLB’s current file, 107,757 licenses hold the B class and 29,124 hold C-10 Electrical.

B General Building and the two-trade rule

A B General Building contractor can run a whole project, but BPC 7057(b) sets a limit. A B can’t take a prime contract involving trades other than framing or carpentry unless one of these is true:

  1. The job involves at least two unrelated trades besides framing or carpentry.
  2. The B contractor holds the specialty license for that trade.
  3. The B contractor subcontracts that trade to a licensed specialty contractor.

Here’s how that plays out:

Job Can a B take the prime contract?
Kitchen remodel with plumbing, electrical and cabinets Yes, it involves several unrelated trades
Rewiring a house, nothing else Only if the B holds a C-10 or subcontracts to a licensed electrician
Replacing a water heater, nothing else Only if the B holds a C-36 or subcontracts to a licensed plumber
Framing or carpentry only Yes, the two-trade limit doesn’t apply to framing or carpentry

CSLB’s ADU guidance also names the B as a class that can build an accessory dwelling unit. See our ADU guide.

B-2 Residential Remodeling

The B-2 is a separate class for residential remodeling, and 1,755 licenses hold it. It’s a different class from the B, with its own scope. If you’re hiring a B-2 for a remodel, read the scope on CSLB’s classification page or ask CSLB whether your project fits.

A General Engineering

The A General Engineering class has its own scope, set by CSLB, and 15,229 licenses hold it. It’s one of the classes eligible for the HAZ certification described below. If an A contractor bids on a home project, read CSLB’s classification page or ask CSLB whether your work falls within the A.

C specialty classes

Most C classes cover one trade. Match the class to the work:

Some C classes come with extra rules. C-8, C-20, C-22, C-39 and C-61/D-49 contractors must carry workers’ comp even with no employees. See how to check workers’ comp. For solar, both the C-46 and C-10 can install photovoltaic systems. See our solar license guide.

The full list is on our license types index.

C-61 Limited Specialty and D subcategories

The C-61 Limited Specialty class is paired with D subcategories, and 19,063 licenses hold it. For example, D-49 is a C-61 subcategory that must carry workers’ comp regardless of employees, and C-61/D-40 is one of the classes eligible for the HAZ certification. When you check a C-61 contractor, read the D subcategory, not just “C-61.”

ASB: asbestos certification

Under BPC 7058.5, work involving 100 square feet or more of surface area of asbestos-containing materials requires either the C-22 Asbestos Abatement class or a qualifier who passed CSLB’s asbestos certification exam (ASB). Contractors doing that work must also register with Cal/OSHA’s Division of Occupational Safety and Health (DOSH) under Labor Code 6501.5.

Two things to watch for:

HAZ: hazardous substance removal certification

The HAZ certification (BPC 7058.7) covers removal and cleanup at listed hazardous sites and the installation or removal of underground storage tanks. It doesn’t cover asbestos work. The qualifier has to pass the hazardous substance certification exam. CSLB’s current application lists these eligible classes: A, B, C-12, C-21, C-36, C-57 and C-61/D-40.

Checking the class on a license

  1. Look up the license with our search, then confirm on CSLB’s Instant License Check.
  2. Read every classification listed, including any D subcategory or certification.
  3. Look for a qualifier replacement note or a class removal pending note. Either one means a classification could drop off the license mid-project.
  4. Match the class to the job using the tables above.

Our license check guide covers the other checks, such as status, bond and workers’ comp.

Sources

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