19-20-608. Member supplemental contribution -- actuarially determined adjustments -- effective dates. (1) (a) Subject to subsections (1)(b) and (1)(c), a tier one member shall contribute to the retirement system a supplemental amount equal to 1% of the member's earned compensation.

(b) The board may decrease the tier one member supplemental contribution if:

(i) the average funded ratio of the system based on the last three actuarial valuations is equal to or greater than 90%; and

(ii) the period necessary to amortize all liabilities of the system based on the most recent annual actuarial valuation is less than 15 years.

(c) Following one or more decreases in the supplemental contribution rate pursuant to subsection (1)(b), the board may increase the supplemental contribution to a rate not to exceed 1% if:

(i) the average funded ratio of the system based on the last three annual actuarial valuations is equal to or less than 80%; and

(ii) the period necessary to amortize all liabilities of the system based on the most recent annual actuarial valuation is greater than 20 years.

(2) (a) Subject to subsection (2)(b), on or after January 1, 2023, the board may require a tier two member to contribute to the retirement system a supplemental amount if:

(i) the average funded ratio of the system based on the last three annual actuarial valuations is equal to or less than 80%;

(ii) the period necessary to amortize all liabilities of the system based on the latest annual actuarial valuation is greater than 20 years; and

(iii) a state or employer contribution rate increase or a flat dollar contribution to the retirement system trust fund has been enacted that is equivalent to or greater than the supplemental contribution rate imposed by the board pursuant to this subsection (2)(a).

(b) A tier two member supplemental contribution increase under this subsection (2) may not:

(i) exceed 0.5% of earned compensation; and

(ii) result in an aggregate tier two member contribution rate of more than 9.15% when added to the normal contribution rate required under 19-20-602.

(c) Following imposition of a supplemental contribution rate increase under this subsection (2), the board may decrease the supplemental contribution rate if:

(i) the average funded ratio of the system based on the previous three annual actuarial valuations is equal to or greater than 90%; and

(ii) the period necessary to amortize all liabilities of the system based on the latest annual actuarial valuation is less than 15 years.

(3) After the board has actuarially determined the need to impose, increase, or decrease a supplemental contribution rate under this section, the imposition, increase, or decrease is effective on the first day of July following the board's determination.