Michigan Compiled Laws, Chapter 500. Insurance Code of 1956 § 500.3821

Sec. 3821. (1) An insurer shall not issue an individual medicare supplement policy to a person who has not applied for or enrolled in medicare, parts A and B. If it is later determined that a person has not applied for or enrolled in medicare, parts A and B, an insurer shall refund all premiums received from the person for a medicare supplement policy issued to the person plus interest less the amount of any benefits received by the person under the policy.

(2) Interest under subsection (1) shall be calculated at 6-month intervals from the date the first premium payment was received at a rate of interest equal to 1% plus the average interest rate paid at auctions of 5-year United States treasury notes during the 6 months immediately preceding July 1 and January 1, as certified by the state treasurer, and compounded annually.