Matching a sub's California license classification to the work
- A specialty sub should hold the C-classification for the trade it's doing: C-10 electrical, C-36 plumbing, C-39 roofing, and so on.
- A specialty contractor can do other-trade work only when it's incidental and supplemental to its own licensed trade.
- A B general building contractor can't take a contract for a single specialty trade other than framing or carpentry, unless the job needs at least two unrelated trades besides framing and carpentry, it holds that classification, or it subcontracts to a licensed specialty contractor.
- Fire protection systems and well drilling need the specific classification no matter what.
Why classification matters
A license that's active but in the wrong classification can leave the work effectively unlicensed for that scope. That brings back the risks in our guide to hiring unlicensed subs: trouble getting paid, CSLB discipline, and workers' comp exposure at audit.
Specialty (C) subs: stay in the lane
A specialty contractor may take a contract involving two or more trades only when the other work is incidental and supplemental to the trade it's licensed for (B&P Code §7059). A C-36 plumber patching drywall after a repipe is one thing. A C-36 taking the whole bathroom remodel, including electrical, is another.
Common matches: C-10 electrical, C-36 plumbing, C-20 HVAC, C-39 roofing, C-8 concrete. Our trades list shows the classification for each of 30 trades.
What a B (general building) license can take
A general building contractor's main business is structures that need at least two unrelated building trades (B&P Code §7057). Under that section:
- A B contractor can take a prime contract or subcontract for framing or carpentry alone.
- For anything else, a B contractor can't take the contract unless it requires at least two unrelated trades other than framing and carpentry, or the B contractor holds the right classification, or (for a prime contract) it subcontracts that work to an appropriately licensed contractor.
- Framing and carpentry don't count toward the two trades.
- Fire protection systems and C-57 well drilling always need that classification or a properly licensed sub.
For a GC hiring subs, the practical point: if you're a B and you hire another B to do just the electrical, ask which classification covers it.
Checklist
- Write the scope in trade termsList each trade the sub will touch, not just "bathroom" or "roof".
- Match each trade to a classification on the recordLook at the classifications on CSLB's record or in Sub Check.
- Is the extra work incidental?If a sub's scope includes a second trade that's more than incidental, split it or confirm they hold that classification.
- Hiring another B for one trade?Confirm they hold the specialty classification, or move that scope to a specialty sub.
- Save the date you checkedClassifications can be added or removed. Keep the record with your subcontract.
General information for California contractors, current as of November 3, 2026. It isn't legal advice; rules change, so check the official source linked above.
More guides
- How to check a California contractor license (CSLB): a GC's checklist
- Workers' comp and subcontractors in California: what GCs should check
- Certificate of insurance checklist for California general contractors
- Additional insured and waiver of subrogation for subcontractors: a California GC's guide
- Risks of hiring an unlicensed subcontractor in California (for GCs)
- Workers' comp premium audits and subcontractors in California: how to prepare
- California contractor's license bond ($25,000): what it covers for a GC