California Code, Education Code - EDC § 22601.5

(a) Any person who is not already a member of the Defined Benefit Program and who is employed by a school district or county office of education to perform creditable service on a part-time basis for less than 50 percent of the time the employer requires for the full-time position is excluded from mandatory membership in the Defined Benefit Program.

(b) Any person who is not already a member of the Defined Benefit Program and who is employed by a community college district to perform creditable service on a temporary basis pursuant to Section 87474, 87478,87480, 87481, 87482, or 87482.5is excluded from mandatory membership in the Defined Benefit Program.

(c) Creditable service performed by a person who is excluded from mandatory membership in the Defined Benefit Program pursuant to this section shall be subject to coverage by the Cash Balance Benefit Program pursuant to Section 26400 if the employer provides the Cash Balance Benefit Program under Part 14 (commencing with Section 26000).