19-2-409. Plans to be funded on actuarially sound basis -- definition. As required by Article VIII, section 15, of the Montana constitution, each system must be funded on an actuarially sound basis. For purposes of this section, "actuarially sound basis" means that contributions to each retirement plan must be sufficient to pay the full actuarial cost of the plan. For a defined benefit plan, the full actuarial cost includes both the normal cost of providing benefits as they accrue in the future and the cost of amortizing unfunded liabilities over a scheduled period of no more than 30 years. For the defined contribution plan, the full actuarial cost is the contribution defined by law that is payable to an account on behalf of the member.