How to Check if a Plumber Is Licensed in California

The CSLB License Lookup

California's Contractors State License Board maintains a public database of every licensed contractor in the state. You can search it at cslb.ca.gov using a license number, a business name, or an individual's name. The lookup is free and returns results instantly.

For plumbers specifically, you're looking for a C-36 Plumbing classification. California doesn't issue individual journeyman or master plumber licenses at the state level — the C-36 is a business entity license that authorizes the holder to contract for plumbing work, pull permits, and employ workers.

What the Lookup Shows You

A CSLB license lookup returns more than a simple yes/no. Here's what each field means:

License Status: The critical field. "Active" means the contractor is currently authorized to perform work. "Suspended," "Revoked," "Expired," or "Cancelled" all mean they cannot legally contract. An "Inactive" license also does not authorize work; check the record for the current status and any associated explanation.

Classification: Confirms the specific trade license held. A C-36 covers plumbing. If the contractor holds multiple classifications (common for general contractors who also hold specialty licenses), they'll all be listed.

Contractor Bond: Shows whether the required $25,000 surety bond is on file. If the bond record is not current, treat the license as a problem even if the headline status reads "Active," and confirm the status with CSLB.

Workers' Compensation: Shows either a workers' comp policy on file or an active Certificate of Exemption. Solo C-36 operators can currently file an exemption, but CSLB's exemption-verification auditing system begins January 1, 2027, and the exemption pathway ends January 1, 2028. If they have employees or helpers on the job and no policy, that's a compliance violation.

Business Information: The legal business name, DBA (if any), entity type (sole proprietor, corporation, LLC), and the qualifier's name.

Complaint Disclosure: If the record lists complaints, citations, or legal actions, check whether each was resolved or resulted in actual disciplinary action; a listing is not itself proof of a violation.

What to Do Before Hiring

Run the lookup before signing anything. Beyond checking that the license is active, verify three things:

1. The classification matches the work. A Class B General Building contractor can manage a multi-trade remodel, but if the project is exclusively plumbing (a repipe, a sewer lateral replacement, a water heater install), the contractor needs a C-36 specifically — or must subcontract the plumbing scope to someone who holds one.

2. The license belongs to the person or company you're dealing with. Some unlicensed operators give out another contractor's license number. Cross-reference the business name on the license with the name on the estimate or contract.

3. The bond and workers' compensation status are current. A lapsed bond means the contractor has no surety protection if they abandon the job or perform defective work. The bond doesn't make you whole automatically — you'd need to file a claim — but its absence is a red flag.

Local Registrations vs the State License

In Los Angeles (both the city and county), some work as a journeyman employee on local or municipal projects can require a separate local credential. The City of Los Angeles Department of Building and Safety (LADBS) and the LA County Department of Public Works each administer their own local system, not the CSLB.

The CSLB license lookup won't show local registrations. If you're hiring a plumbing company and want to verify that the individual plumber sent to your home holds local credentials where required, contact the relevant municipal building department.

When the License Shows a Problem

If the lookup reveals a suspended, revoked, or expired license, don't hire the contractor — even if they claim it's a clerical issue being resolved. Work performed under an invalid license can trigger serious consequences under California Business and Professions Code § 7031. A client can refuse to pay for the work and can seek disgorgement of amounts already paid.

If a contractor you've already hired turns out to be unlicensed or operating under a suspended license, you can file a complaint with the CSLB directly through their website or by calling their consumer hotline. Beginning July 1, 2026, unlicensed contracting carries administrative civil penalties of $1,500 to $15,000 per violation and potential criminal misdemeanor charges under BPC Section 7028, including up to six months in county jail and a $5,000 fine for a first offense.

For plumbers navigating the licensing process from the other side — getting the C-36, documenting experience, passing the exams — the California Plumber License Guide walks through the full application sequence from apprentice experience through active license.

See more California guides →