(1) For purposes of determining the PERS GABA rates referenced in 19-3-1605(5), MCA, the actuary will:

(a) reduce the 1.5% GABA rate established in 19-3-1605(4), MCA by 0.1% for each full 2 percentage points the funded percentage is below 90%;

(b) establish a GABA rate expressed in tenths of a percent.

(2) This rule will not apply until the PERS amortization period is under 40 years.

(3) Once the PERS amortization period is under 40 years, the actuary will adjust the 1.5% GABA each year, based on that year's funding percentage.