Gov. Code, § 20581

If a public agency that terminated its contract enters into a contract for participation in this system, the contract may provide for increase in benefits of persons retired or members who retained rights under this system, if the benefits were reduced under this article at the time of termination, to the level provided in the contract for members, and for redeposit of any contributions for service to the agency not credited under a local system maintained by the agency after termination, withdrawn at termination by a person who becomes a member on contract date. Unless the redeposit is made, the member shall not receive credit for the service. All service rendered prior to the contract date and credited as a result of the contract shall constitute prior service whether or not rendered during the period of the terminated contract. All liabilities for service performed under the terminated contract shall become liabilities of a plan under the new contract. The ratio of assets to liabilities that existed at the time the previous contract was terminated shall be used to calculate the amount of assets to be transferred to a plan under the new contract.