Cal. Gov. Code § 31648.4
In any county in which the board of supervisors has entered into an agreement as permitted by Section 20569.2, the governing body of the contracting agency from which the employees were transferred or the governing body of the district or the county service area to which the employees were transferred may pay all or part of the cost, as determined by the board, of the liabilities which were assumed by the county system under Section 20569 and which exceed the value of the cash or securities of both transferred by the Public Employees' Retirement System to the county system. The governing bodies of the contracting agency and of the district or the county service area may determine the proportion of the liabilities each pays.
Ca. Gov. Code § 31648.4