Mich. Comp. Laws § 205.8

Sec. 8. If a taxpayer files with the department a written request that copies of letters and notices regarding a dispute with that taxpayer be sent to the taxpayer's official representative, the department shall send the official representative, at the address designated by the taxpayer in the written request, a copy of each letter or notice sent to that taxpayer. A taxpayer shall not designate more than 1 official representative under this section for a single dispute.