(a) A person serving as district attorney, supernumerary district attorney, or who has made an election to assume the office of supernumerary district attorney or is otherwise entitled to participate in the supernumerary district attorney program established under Division 2 of this article shall, subject to subsection (c), continue to serve or participate in the supernumerary district attorney program, which shall include the assumption of the office of the supernumerary district attorney after November 8, 2016 according to the terms and conditions of Division 2 of this article, notwithstanding the fact that the person may be re-elected after November 8, 2016 to the office he or she is holding on November 8, 2016.

(b) No person may participate in both the supernumerary district attorney program and the Employees' Retirement System based on the same service.

(c) A district attorney who was elected prior to November 8, 2016 and who is serving in the capacity of district attorney on and after November 8, 2016 and had prior service credit in the Employees' Retirement System, Teachers' Retirement System, or Judicial Retirement Fund prior to being elected district attorney shall have 30 days from November 8, 2016 to elect to participate in the District Attorneys' Plan established by this division. This election shall be irrevocable.

(d) An assistant or deputy district attorney who obtains service credit in that position as a Tier 1 plan member and is elected or appointed district attorney on or after November 8, 2016, may withdraw from service after completion of not less than 25 years of credible service and may retire without a reduction in retirement allowance upon written application to the Board of Control setting forth at what time, not less than 30 days nor more than 90 days subsequent to the execution and filing thereof, he or she desires to be retired.