California Code, Welfare and Institutions Code - WIC § 14043.45

(a) Notwithstanding whether a National Provider Identification (NPI) number is required by the rules issued by the Centers for Medicare and Medicaid Services implementing the Health Insurance Portability and Accountability Act of 1996 (HIPAA), the department may require that an applicant or provider submit an NPI number.

(b) For transactions not specifically identified as covered transactions under the HIPAA NPI rules, the department may require that a provider use a National Provider Identification number on those transactions, or the department may issue the provider a unique identification number or numbers that shall be used on all transactions.

(c) Notwithstanding any other provisions of law, the department may, without taking regulatory action pursuant to Chapter 3.5 (commencing with Section 11340) of Part 1 of Division 3 of Title 2 of the Government Code, implement, interpret, or make specific this section by means of a provider bulletin or similar instruction. The department shall notify and consult with interested parties and appropriate stakeholders in implementing, interpreting, or making specific this statute, including taking all of the following actions:

(d) This section shall apply to any health care program administered by the department or its agents or contractors.