How to check a plumber’s license on CSLB

The California Contractors State License Board (CSLB) runs a free public license lookup. CSLB says contractors must show their state license number in ads, on business cards, and on bids and contracts — and that seeing a number does not mean the license is valid, so you still need to check it (CSLB: finding the right contractor).

Step by step

Get the license number. Ask for it, or find it on the estimate, truck, website or ad. California contractor license numbers are digits only (up to 8).
Open CSLB’s Check a License page and enter the number. If you only have a name, CSLB’s search tips say to type the last name first for names with a first and last name, and to try fewer characters if nothing comes up. CSLB’s page may ask you to complete a security (CAPTCHA) check.
Check that the business name matches the company that gave you the estimate.
Check the status. You want an active license. If the status shows anything else, ask the business to explain and consider choosing another.
Check the classification. Plumbing work is the C-36 Plumbing classification. CSLB’s official description of C-36 includes water and gas piping from the owner’s side of the utility meter, gas appliance connections, equipment to heat water, and on-site waste disposal connections (CSLB C-36). Other work (for example forced warm-air heating) falls under other classifications.
Check the expiration date, bond and workers’ compensation. California licensed contractors must have a $25,000 contractor license bond; CSLB cautions that it does not assure a contractor’s competence and may not cover larger projects. If the contractor has employees they must carry workers’ compensation; a contractor with no employees can file an exemption (CSLB’s page notes some classifications, such as C-20 and C-39, must carry it regardless).
Look for disclosures. CSLB says the lookup includes complaint disclosure information.
Check the person. CSLB advises asking to see the pocket license and a photo ID and making sure the person matches the license. Salespeople must be registered as Home Improvement Salespersons.

Paperwork and payment tips from CSLB

Get at least three written bids on the same scope of work, and be careful with a bid much lower than the others.
Get a written contract. CSLB’s ten tips say to avoid paying more than 10% down or $1,000, whichever is less, to avoid paying in cash, and to avoid letting payments get ahead of the work (CSLB 10 tips).
You can also call CSLB at (800) 321-CSLB (2752).

About the “Verify at CSLB” links in this directory

Every listing shows the license number from CSLB’s public License Master file (downloaded October 26, 2026) with a link to CSLB. If a link does not open the license record directly, copy the license number into CSLB’s Check a License page above. This directory does not endorse or guarantee any business, and a listing only means the CSLB file showed an active C-36 license on that date.

General information only. This directory is not a contractor and does not give plumbing advice or quotes. It does not know which listed businesses take which jobs — contact the business directly, verify its license at CSLB, and make your own decision. You contract with and pay the business directly.

Next steps

Browse Lancaster or Palmdale licensed-plumber listings, and read how to check a license on CSLB.