Mich. Comp. Laws § 257.521: Motor vehicle liability policy; notice of termination.

Sec. 521.

When an insurance carrier has certified a motor-vehicle liability policy under section 518 or section 519, the insurance so certified shall not be cancelled or terminated until at least 10 days after a notice of cancellation or termination of the insurance so certified shall be filed in the office of the secretary of state, except that such a policy subsequently procured and certified shall, on the effective date of its certification, terminate the insurance previously certified with respect to any motor vehicle designated in both certificates.