Sec. 2.02. ACTUARIAL ASSUMPTIONS. (a) If the amount of any benefit or contribution is to be determined on the basis of actuarial assumptions that are not otherwise specifically set forth for that purpose in this article, the actuarial assumptions to be used are those earnings and mortality assumptions being used on the date of the determination by the pension system's qualified actuary and approved by the board.

(b) The actuarial assumptions being used at any particular time shall be attached by the executive director as an addendum to this article and treated for all purposes as a part of any plan created by this article. The executive director shall promptly update any addendum to conform to any changed actuarial assumptions approved by the board.

(c) The actuarial assumptions may be changed by the pension system's qualified actuary at any time if approved by the board, but no such change in actuarial assumptions may result in any decrease in benefits accrued as of the effective date of the change.

For expiration of this section, see Subsection (e).