[§87A-31.5]  Employer contributions
irrevocable.  Notwithstanding any law to the contrary, all of the monthly
contributions that the State and counties make to the fund under sections
87A-32, 87A-33, 87A-34, 87A-35, 87A-36, and 87A-37, and all other contributions
that the State and counties may make to the fund, shall be irrevocable;
provided that this shall not preclude the fund from returning contributions or
payments made by the State or any county under a mistake of fact within one
year after the payment of the contributions or payments. [L 2006, c 57, §2]