Instead of the normal rates of contribution required by Section 31639.25 the board may, upon actuarial advice, establish a single rate of contributions applicable to all persons becoming members after this section is made operative in that county by the board. However, this rate shall be such as to provide the average annuity described in Section 31639.25.
Source:
Section 31639.26, https://leginfo.legislature.ca.gov/faces/codes_displaySection.xhtml?lawCode=GOV§ionNum=31639.26..