(A) A member may purchase in portionsall or part of the exempt service credit that the member is eligible to purchase. Payment for any portion purchased shall be made in full at the time of purchase. A member may make subsequent purchases of any remaining exempt service credit at any time prior to retirement.
(1) If the credit to be purchased is for service that would have been covered under Chapter 3309. of the Revised Code, the system shall request certification of the service from the employer for which the service was performed. On the basis of the employer certification, the system shall determine the amount of service credit that would have been earned had the service not been exempt.
(2) If the credit to be purchased is for service that would have been covered under Chapter 145. or 3307. of the Revised Code, the system shall request certification from the applicable retirement system that the service was exempt and the amount of service credit, based upon the certification of the employer for which the service was performed, that would have been earned had the service not been exempt.
(3) The service credit determined under paragraphs (B)(1) and (B)(2) of this rule shall be reduced to the extent that:
(a) It is concurrent with any other credit that will be used in calculating a benefit;
(b) Its purchase will result in the member being credited with more than twelve months of service credit in any one year.
(C) The member shall be eligible to purchase the credit determined pursuant to paragraph (B) of this rule. The system shall calculate the cost to purchase each year of credit by multiplying the member's compensation for the twelve months of contributing service under Chapter 145., 3307. or 3309. of the Revised Code immediately preceding the month in which the application to purchase is received by a percentage rate established by the board by resolution upon recommendation of its actuary. The cost for portions of credit of less than a full year shall be prorated on the basis of the cost for a full year.