Cal. Educ. Code § 22504

(a) Any person employed by a school district or county office of education to perform creditable service on a part-time basis, who is not already a member of the Defined Benefit Program, shall become a member as of the first day of the pay period following the pay period in which the person performed at least 60 hours of creditable service, if employed on an hourly basis, or 10 days of creditable service, if employed on a daily basis, during the school year, in one school district or county office of education, unless excluded from membership pursuant to Section 22601.

(b) Any person employed by a community college district to perform creditable service on a part-time basis, who is not already a member of the Defined Benefit Program, shall become a member as of the first day of the pay period following his or her employment to perform creditable service that is not subject to Section 87474, 87480, 87481, 87482, or 87482.5, unless excluded from membership pursuant to Section 22601.

(c) Subdivision (a) does not apply to persons who perform service subject to coverage under this part and who are employed by employers who provide benefits for their employees under Part 14 (commencing with Section 26000).