California Code, Welfare and Institutions Code - WIC § 14043.62

(a) The department shall deactivate, immediately and without prior notice, the provider's number, including all business addresses used by a provider to obtain reimbursement from the Medi-Cal program when warrants or documents mailed to a provider's mailing address or its pay to address, if any, or its service or business address, are returned by the United States Postal Service as not deliverable or when a provider has not submitted a claim for reimbursement from the Medi-Cal program for one year. Prior to taking this action the department shall use due diligence in attempting to contact the provider at its last known telephone number and ascertain if the return by the United States Postal Service is by mistake or shall use due diligence in attempting to contact the provider by telephone or in writing to ascertain whether the provider wishes to continue to participate in the Medi-Cal program. If deactivation pursuant to this section occurs, the provider shall meet the requirements for reapplication as specified in this article or the regulations adopted thereunder.

(b) For purposes of this section: