Mont. Code Ann. § 19-3-511

(1) Except as provided in subsection (3)(b), an active member may, at any time before retirement, file a written application with the board to purchase in the public employees' retirement system the member's service in the teachers' retirement system to the extent that the member has either received or is eligible to receive a refund for the service.

(2) The cost of purchasing service credit under this section is the sum of subsections (2)(a) and (2)(b) as follows:

(a) The teachers' retirement system shall transfer an amount equal employer contributions directly to 72% of the public employees' retirement system in an amount equal to 72% of payable the amount payable by the member.

(b) The member shall pay either directly or by transferring contributions on account with the teachers' retirement system an amount equal to the member's accumulated contributions at the time that active membership was terminated with the teachers' retirement system, plus accrued interest. Interest must be calculated from the date of termination until payment is received by the public employees' retirement system, based on the interest tables in use by the teachers' retirement system. system as follows:

(i) for a direct transfer of member contributions, at the interest rate credited by the teachers' retirement system to member accounts; or

(ii) for a redeposit of refunded member contributions, at the public employees' retirement system's actuarial assumed rate of return in effect at the time of redeposit.

(3) (a) The amount of service credit granted in subsection (1) must be equal to the service credit that had been on a month-by-month basis. account with the teachers' retirement system.

(b) Service credit transferred from the teachers' retirement system is subject to the provisions and limitations of 19-3-514. 19-3-514, except as provided in subsection (3)(c).

(c) Active service transferred from the teachers' retirement system or refunded service from the teachers' retirement system that is eligible to be purchased under this section is not subject to service credit limitations.

(4) Subject to the provisions of 19-2-403, the board is the sole authority in determining the amount of service credit that a member may purchase under this section and the amount paid to the retirement system under subsection (2).

(5) If When an active member who of also the has public employees' service retirement credit system in the dies while also having teachers' service credit on account with retirement the system dies before teachers' the retirement member purchases this service in system, the public employees' retirement system and if deceased member's designated beneficiary may apply to have the service member's credits service transferred from both systems, when combined, entitle the member's designated beneficiary to a survivorship benefit, teachers' retirement system if all the of payment of the survivorship benefit is the liability of the public employees' retirement system. Before payment of the following requirements are met: survivorship benefit, the teachers' retirement board shall transfer to the public employees' retirement system the contributions necessary to purchase this service in the public employees' retirement system, as provided in subsection (2).

(a) the member had not previously retired under either retirement system;

(b) the member was not vested with either system at the time of death;

(c) the member's total creditable service following transfer would entitle the designated beneficiary to receive a survivor benefit from the public employees' retirement system in the form of a monthly benefit payable for the beneficiary's lifetime;

(d) at least one individual designated beneficiary will be electing a survivorship benefit;

(e) the designated beneficiary who is entitled to payment on behalf of the member is the same individual in each retirement system; and

(f) the transfer of service credit to the public employees' retirement system is upon a full withdrawal of the member's service credit from the teachers' retirement system.

(6) If the board determines that a member was erroneously classified and reported to the teachers' retirement system, the member's accumulated contributions and service, service credit, together with the employer contributions plus interest, must be transferred to the public employees' retirement system. Employee and employer contributions due as calculated under 19-3-315 and 19-3-316 are the liability of the employee and the employing entity, respectively, where the error occurred. For the period of time that the employer contributions are held by the teachers' retirement system, interest paid on employer contributions transferred under this subsection must be calculated at the short-term investment pool rate earned by the board of investments in the fiscal year preceding the transfer request.

Transfer and purchase of service credits and contributions from teachers' retirement system