Section 39.30.420 - Amendment and termination of plan(a) The state has the right to amend the plan at any time and from time to time, in whole or in part, including the right to make retroactive amendments referred to in 26 U.S.C. 401(b).(b) The plan administrator may not modify or amend the plan retroactively in such a manner as to reduce the benefits of any member accrued to date under the plan by reason of contributions made before the modification or amendment except to the extent that the reduction is permitted by the Internal Revenue Code.(c) The state may, in its discretion, terminate the plan in whole or part at any time without liability for the termination. If the plan is terminated, all investments remain in force until all individual accounts have been completely distributed under the plan, and, after all plan liabilities are satisfied, excess assets revert to the employer.(d) Any contribution made by an employer to the plan because of a mistake of fact must be returned to the employer by the administrator within one year after the contribution or discovery, whichever is later.