California Code, Government Code - GOV § 21022

“Public service,” with respect to a local member who is a full-time employee, also means any time on or after January 1, 1981, but not to exceed 12 months, during which the local member is laid off.  In the event the member becomes subject to membership through employment in another member classification during the layoff period, any service credit accumulated through and contributions associated with the intervening employment shall be revoked upon election by the member to purchase public service credit as provided by this section.  The service credit provided by this section shall not exceed one year for each layoff period and shall be provided to any person who:  (1) returns within 12 months of the date of layoff to full-time employment under the procedures of the employer for returning laid-off employees to work;  (2) elects to purchase the public service credit within three years of return to work or the effective date of the contract amendment to become subject to this section;  and (3) redeposits any contributions which had been withdrawn at the commencement of, or during, the period of the layoff.

This section shall not apply to any contracting agency nor to the employees of a contracting agency until the agency elects to be subject to this section by contract or by amendment to its contract made in the manner prescribed for approval of contracts.