1. The “Income-Expense Fund” is hereby created. It is the fund to which shall be credited all investment income from invested assets of the system, and in which shall be accumulated the contributions made by employers for the administrative expenses of the system, and from which shall be made annual transfers of investment credits to the other funds of the system, and from which shall be paid all the expenses of the board necessary for the administration and operation of the system.

2. When paid to the system, the employer contributions provided for in subsection 5 of section 70.730 shall be credited to the income-expense fund.

3. The board may accept gifts and bequests, and they shall be credited to the income-expense fund, along with all other moneys received by the system, the disposition of which is not specifically provided for in sections 70.600 to 70.760.

4. At the end of each system fiscal year the board shall credit each member’s individual account in the members deposit fund with regular interest on the largest balance remaining in such account for the entire fiscal year. At the end of each system fiscal year the board shall credit to each account in the employer accumulation fund regular interest on the mean balance in such fund for the fiscal year, and similarly shall credit regular interest to the benefit reserve fund and to the casualty reserve fund. Such regular interest shall be transferred from the income-expense fund.

5. Whenever the board determines that the balance in the income-expense fund is more than sufficient to cover the current charges to the fund, the board may by resolution provide for contingency reserves, or for the transfer of such excess or portions thereof to cover the needs of the benefit reserve fund or the casualty reserve fund.