(1) The governing board vested with the general administration, management, and operation of a system or other decision-making body that is responsible for implementation and supervision of any system shall confirm in the annual actuarial valuation required under section 20h and the summary annual report required under section 13 that each system under this act provides for the payment of the required employer contribution as provided in this section and shall confirm in the summary annual report that the system has received the required employer contribution for the year covered in the summary annual report. The required employer contribution is the actuarially determined contribution amount. An annual required employer contribution in a system under this act shall consist of a current service cost payment and a payment of at least the annual accrued amortized interest on any unfunded actuarial liability and the payment of the annual accrued amortized portion of the unfunded principal liability. For fiscal years that begin before January 1, 2006, the required employer contribution shall not be determined using an amortization period greater than 40 years. Except as otherwise provided in this section, for fiscal years that begin after December 31, 2005, the required employer contribution shall not be determined using an amortization period greater than 30 years. For the Tier 1 retirement plan under the state employees’ retirement system, created under the state employees’ retirement act, 1943 PA 240, MCL 38.1 to 38.69; the Michigan public school employees’ retirement created under the public school employees retirement act of 1979, 1980 PA 300, MCL 38.1301 to 38.1437; and the Michigan state police retirement system created under the state police retirement act of 1986, 1986 PA 182, MCL 38.1601 to 38.1675, only, for the fiscal year beginning October 1, 2006, the contribution for the unfunded actuarial accrued liability shall be equal to the product of the assumed real rate of investment return times the unfunded actuarial accrued liability. In a plan year, any current service cost payment may be offset by a credit for amortization of accrued assets, if any, in excess of actuarial accrued liability. A required employer contribution for a system administered under this act shall allocate the actuarial present value of future plan benefits between the current service costs to be paid in the future and the actuarial accrued liability. The governing board vested with the general administration, management, and operation of a system or other decision-making body that is responsible for implementation and supervision of a system shall act upon the recommendation of an actuary and the board and the actuary shall take into account the standards of practice of the actuarial standards board of the American academy of actuaries in making the determination of the required employer contribution.

    (2) Subsection (1) applies to a large sponsored system except as otherwise provided in a plan for adjustment. As used in this subsection, “plan for adjustment” means that term as defined in section 13g.