Cal. Gov. Code § 31641.6
An employee of a city who has become a county employee upon the assumption by the county of the functions of the city department in which he was employed, may, if he is not covered by the city under a contract with the Public Employees' Retirement System, elect to receive credit in the county retirement system for service for the city prior to the cessation of his employment by the city. When such person elects to receive credit, membership in the retirement system shall commence with the first day of the month in which credit is granted.
Any such person shall be entitled to credit in the county retirement system for service performed for the city when and if (a) the board of retirement receives certification from the city of the city service and earnable compensation of the employee; and (b) the employee deposits into the employees' retirement system the amount of contributions he would have made had he been a county employee during his city employment; and (c) there is also deposited in the employees' retirement system by the city, the employee, or both, the amount that the county would have been required to deposit to the employees' retirement fund based on the city salary paid to such employee.
Upon deposit of such funds, the employee's age at entry shall be considered to be his age at time of employment with the city or at the time this chapter was effective in the county whichever is later. Such money deposited under (b) above shall be considered as accumulated normal contributions of the employee and any such money deposited under (c) above shall be considered as contributions of the employer county.
If all of the money called for under (b) above is not paid within 90 days after employment by the county, only the part of city employment latest in date covered by such deposit shall be credited and the age at entry and the amount under (c) above shall be adjusted accordingly.
An employee shall receive credit for city employment prior to his employment by the county only for such service for which he is not entitled to receive a pension or retirement from such city.
This section shall become operative in any county on the first day of the calendar month after the board of supervisors adopts by four-fifths vote a resolution making it operative in the county.
Ca. Gov. Code § 31641.6