Subject to Section 20588, whenever, as a result of the assumption by a county, fire authority, or district of firefighting or law enforcement functions performed by a public agency or the state subject to the Public Employees’ Retirement Law, any person ceases to be employed by a public agency or the state and is employed by a county, fire authority, or district in which this chapter has become operative, that person shall become a member of the retirement system of a county immediately upon entering county service. That member of the county retirement system shall be entitled to service credit in the county retirement system for the service for which he or she was entitled to credit in the Public Employees’ Retirement System at the time of cessation of employment by the public agency or the state, without necessity of payment of any additional contributions in respect to that service, when and if all of the following occur:

1. (a) The board of retirement receives certification from the Board of Administration of the Public Employees’ Retirement System of the service with which the person was entitled to be credited by the Public Employees’ Retirement System at the time of cessation of his or her public agency or state employment.
2. (b) There is paid into the county retirement fund of the county, an amount equal to the normal contributions of the person to the Public Employees’ Retirement System, together with all interest credited thereto, which amount shall be credited to the individual account of the member in the county retirement system, and shall thereafter for all purposes be deemed to be the member’s contribution to the county retirement system with respect to the service so certified.
3. (c) There is paid to the retirement system of the county an amount equal to all contributions of the public agency or the state made to the Public Employees’ Retirement System on account of service rendered by the person together with interest credited to the public agency or the state thereto.

4. (d) The board of retirement elects to apply this section as a prudent means of mitigating against potential adverse financial impact upon the county retirement system from the cost of disability retirements that may be applied for in the future by persons injured while being employed by the county, fire authority, or district after ceasing to be employed by a public agency or the state as a result of the assumption by a county, fire authority, or district of firefighting or law enforcement functions.

   This section shall apply in a county of the first, the second, the seventh, or the fourteenth class, as defined by Section 28020, as amended by Chapter 1204 of the Statutes of 1971, and Section 28022, as amended by Chapter 43 of the Statutes of 1961, and Sections 28023, 28028, and 28035, as amended by Chapter 1204 of the Statutes of 1971.