Michigan Compiled Laws, Chapter 500. Insurance Code of 1956 § 500.2025

(1) In the case of any contract of life insurance or life annuity, paying bonuses to policyholders or otherwise abating their premiums in whole or in part out of surplus accumulated from non-participating insurance: Provided, That any such bonuses or abatement of premiums shall be fair and equitable to policyholders and for the best interest of the company and its policyholders;

(2) In the case of life insurance policies issued on the industrial debit plan, making allowance to policyholders who have continuously for a specified period made premium payments directly to an office of the insurer in an amount which fairly represents the saving in collection expense;

(3) Readjustment of the rate of premium for a group insurance policy based on the loss or expense experience thereunder, at the end of the first or any subsequent policy year of insurance thereunder, which may be made retroactive only for such policy year.