Mont. Code Ann. § 19-3-412

(1) Except as provided in 5-2-304 and subsection (2) of this section, (2), the following employees and elected in officials in covered positions that are not elected offices shall elect either to become active members of the retirement system or to decline this optional membership by filing an irrevocable, written application with the board in the manner prescribed in subsection (3):

(a) elected officials of the state or local governments, including individuals appointed to fill the unexpired employees serving in employment that does not cumulatively exceed a total term of elected officials, who: 960 hours of covered employment with all employers under this chapter in any fiscal year;

(i) are paid on a salary or wage basis rather than on a per diem or other reimbursement basis; or

(ii) were members receiving retirement benefits under the defined benefit plan or a distribution under the defined contribution plan at the time of their election;

(b) employees serving in employment that does not cumulatively exceed a total of 960 hours of covered directly appointed by the governor; employment with all employers under this chapter in any fiscal year;

(c) employees directly appointed by working 10 months or less for the governor; legislative branch to perform work related to the legislative session;

(d) employees working 10 months or the less for the legislative branch to perform work related to the legislative session; chief administrative officer of any city or county; and

(e) the chief administrative officer employees of any city county hospitals or county;

(f) employees of county hospitals or rest homes.

(2) A member who is elected to a local government position in which the member works less than 960 hours in a calendar year may, within 90 days of being elected, decline optional membership with respect to the member's elected position.

(2) (a) An employee who is an active or inactive member at the time of employment is not eligible to make an election under subsection (1). Upon employment in the position, an employee who was an active member remains an active member for all covered employment and an employee who was an inactive member shall become an active member.

(b) A person who was a retired member before employment in a position for which membership is optional under subsection (1) is not eligible to make an election under subsection (1) and is subject to the provisions of Title 19, chapter 3, part 11.

(3) (a) The board shall prescribe the form of the written application required pursuant to subsection (1) and provide written application forms to each employer.

(b) Each employee or elected official in a position covered under subsection (1) shall obtain the written application form from the employer and complete and return it to the board.

(c) The written application must be filed with the board: board within 90 days after the commencement of the employee's employment.

(i) for an employee described in subsection (1)(d), within 90 days of the commencement of the employee's employment; and

(ii) for an employee or elected official described in subsection (1)(a), (1)(b), (1)(c), (1)(e), or (1)(f), within 90 days of the commencement of the employee's or elected official's employment.

(d) The employer shall retain a copy inform of the employee of the employee's or elected official's written application. option to elect membership and retain a copy of the employee's written application.

(4) If the Failure employee to or elected official fails to file the written application required inform an employee in a position covered under subsection (1) with of the board within the time allowed in subsection (3), the employee or elected official waives membership. employee's option to elect membership must be treated as a correction of a reporting error under 19-2-506(4). An employee who elects membership in the defined benefit plan following discovery of an omission to be informed of the optional election may choose to purchase the retroactive service under 19-3-505, and the employer is obligated to pay the employer contributions as well as accrued interest in both the employer and employee contributions.

(5) An If the employee or elected official who declines optional membership may not receive membership service or service credit fails to file with for the employment for which membership was declined. board the written application required under subsection (1) within the time allowed in subsection (3), the failure must be considered an election to decline

(6) An Except as provided in subsection (7), an employee or who elected official who declined declines optional membership but later becomes a member may purchase not receive membership service or service credit for the period of time beginning with the date of employment in for which membership was declined to the commencement of membership. Purchase of service credit pursuant to this subsection must declined. comply with 19-3-505.

(7) Except as provided in subsection (2), An employee who declined membership optional in the retirement system is not optional for an employee or elected official who is membership but later becomes already a member. Upon employment in a position member may purchase service credit for which membership is optional: the period of time beginning with the date of employment in which membership was declined to the commencement of membership. Purchase of service credit pursuant to this subsection must comply with

(a) a member who was an active member before the employment remains an active member;

(b) a member who was an inactive member before the employment becomes an active member; and

(c) a member who was a retired member before the employment is subject to part 11 of this chapter.

(8) An employee who has made an election under this section may not make a new or different election under this section in any circumstance unless the employee has been terminated from employment in all optional membership positions for at least 30 days.

(8) (a) An employee who declines membership for a position for which membership is optional may not later become a member while still employed with the same employer but in a different optional membership position.

(b) An elected official who declines membership for a position for which membership is optional may not later become a member if reelected to the same optional membership position.

(c) If, after a break in service of 30 days or more, an employee who was employed in an optional membership position is reemployed in the same position or is employed in a different position for which membership is optional, the employee shall again choose or decline membership.

(d) If the break in service is less than 30 days, an employee who declined membership is bound by the employee's original decision to decline membership.

(9) An employee accepting a position that requires membership must shall become a member even if the employee previously declined membership and did not have a 30-day break in service. under this section.

Optional membership – employees not in elected office