(1) Members of an MPERA-administered retirement system who are eligible to and wish to purchase military, federal volunteer, one-for-five, out-of-state, Montana public service, or other public service from a previous retirement system to their current retirement system must pay the actuarial cost of that service.
(2) The actuarial cost of the service is determined as follows:
(a) The member's age and membership service as of the date of the request, each rounded to the nearest whole year, is used to determine the actuarial factor related to the number of years service to be purchased.
(b) The actuarial factor determined in (2)(a) is then multiplied by the member's compensation for the immediately preceding 12 months to determine the cost of the service to be purchased.
(3) A member of a retirement system is eligible to purchase only that service permitted to be purchased by statute.