California Code, Public Contract Code - PCC § 6100

(a) A state agency, as defined in Section 10335.7 that is subject to this code, shall, prior to awarding a contract for work to be performed by a contractor, as defined by Section 7026 of the Business and Professions Code, verify with the Contractors State License Board that the person seeking the contract is licensed in a classification appropriate to the work to be undertaken. Verification as required by this section need only be made once every two years with respect to the same contractor.

(b) In lieu of the verification, the state entity may require the person seeking the contract to present his or her pocket license or certificate of licensure and provide a signed statement which swears, under penalty of perjury, that the pocket license or certificate of licensure presented is his or hers, is current and valid, and is in a classification appropriate to the work to be undertaken.