Cal. Gov. Code § 31629
If a former member does not file proper application for the return of his accumulated contributions within five years after date of such notice to him, such accumulated contributions shall be deposited in and become a part of the current pension reserve fund, and thereafter the fund shall not be liable to such member for any portion of his accumulated contributions.
However, notwithstanding the fact that such an application has not been filed, the board of retirement may, in its sound discretion authorize the return of any deposit account 90 days after the 90-day notice referred to in Section 31628, provided that the former employee had less than five years' service credit with the county.
No return of any deposit account may be made by mail pursuant to this section unless the letter provided for in Section 31628 was receipted for by the former member and the signed receipt is in the possession of the board of retirement or the county treasurer.
The amendment of this section enacted during the 1975-76 Regular Session shall be effective with respect to persons first becoming members of a retirement system on and after January 1, 1976.
Ca. Gov. Code § 31629