California Code, Education Code - EDC § 24201

(1) The member has attained 55 years of age or more and has at least five years of credited service, at least one year of which has been performed subsequent to the most recent refund of accumulated retirement contributions. The five years of credited service may include out-of-state service purchased pursuant to Section 22820. The number of years of credited service performed in California shall not be less than the number of years necessary to determine final compensation pursuant to Section 22134 or 22135, whichever is applicable to the member.

(2) The member is credited with service that is not used as a basis for benefits under any other public retirement system, excluding the federal social security system, if the member has attained 55 years of age or older and retires concurrently under one or more of the retirement systems with which the member has concurrent membership as defined in Section 22115.2.