Cal. Fin. Code § 15304

After the meeting or the written vote of the members, the credit union shall take such action as is necessary to make it a federal credit union, and within 10 days after receipt of the federal charter, the credit union shall file with the commissioner and with the Secretary of State, a copy of the charter issued to such credit union by the National Credit Union Administration or a certificate showing the organization of such credit union as a federal credit union certified by or on behalf of the National Credit Union Administration. Upon the filing of such instrument with the Secretary of State the credit union ceases to be a state credit union and is a federal credit union.