Section 31591 - Interest credited(a) Regular interest shall be credited semiannually on June 30th and December 31st to all contributions in the retirement fund which have been on deposit for six months immediately prior to that date. Interest at the rate of 21/2 percent per annum, until otherwise determined by the board, compounded semiannually, shall be used in the calculation of benefits under any mortality table adopted by the board of supervisors.(b) No interest shall be credited to a member's account after the membership of the member in the retirement association has ceased, except under any of the following circumstances:(1) The former member has left his or her accumulated contributions in the retirement fund and has either elected, in writing, a deferred retirement allowance, or is eligible to so elect under Section 31700 but has failed to do so.(2) The surviving spouse of a deceased member or the legally appointed guardian of the member's unmarried children under age 18 has elected to leave a death benefit on deposit as provided for in Section 31781.2.(3) The former member, regardless of service, has left his or her accumulated contributions in the retirement fund and has not terminated employment.Amended by Stats. 1997, Ch. 43, Sec. 1. Effective January 1, 1998.