The average compensation during any period of service as a member of the Public Employees’ Retirement System, a member of the Judges’ Retirement System or Judges’ Retirement System II, a member of a retirement system established under this

chapter in another county, a member of the State Teachers’ Retirement System, or a member of a retirement system of any other public agency of the state that has established reciprocity with the Public Employees’ Retirement System subject to the conditions of

Section 31840.2, shall be considered compensation earnable or pensionable compensation pursuant to

Section 7522.34, whichever is applicable, by a member for purposes of computing final compensation for that member provided: (

a) The period intervening between active memberships in the respective systems does not exceed days, or months if

Section 31840.4 applies. That period shall not include any time during which the member was prohibited by law from becoming a member of the system of another county. Notwithstanding anything in this

chapter to the contrary, the 90-day or 6-month restriction referred to in this

section or any other provision of this

chapter affecting deferred retirement shall not be applicable to any members who left county or district service prior to October 1, 1949, and subsequently redeposited. (

b) He or she retires concurrently under both systems and is credited with the period of service under that other system at the time of retirement. The provisions of this

section shall be applicable to all members and beneficiaries of the system.