Michigan Compiled Laws, Chapter 500. Insurance Code of 1956 § 500.451

Sec. 451. Any unauthorized insurer transacting insurance in this state shall be subject to a tax of 2% of premiums written in this state and to an additional regulatory fee of 0.5% on premiums written in this state.The tax required by this section shall be considered delinquent if not paid within 30 days after a copy of the computation of the tax by the commissioner is delivered to the insurer in the manner prescribed by law for the service of process.