Michigan Compiled Laws, Chapter 339. Occupational Code § 339.5815

Sec. 815.  (1) If an individual who is an employee of a person, or who is an officer of a person that is not an individual, and who is authorized to perform installations, alterations, or servicing in any of the work classifications described in section 807(2),  1 is designated as the contractor of record for that person under section 809   2 and ceases to be an employee or officer of that person, the person has 90 days after the date the contractor of record ceases to be an employee or officer in which to designate an employee or officer who is a holder of a mechanical contractor's license as the new contractor of record.  The person shall notify the department in writing of the designation.

(2) If an individual is licensed to perform installations, alterations, or servicing in 1 or more of the work classifications described in section 807(2) and is also the contractor of record, and that individual ceases to do business as a mechanical contractor and sells his or her business interest to another person, the buyer has 90 days to designate an employee or officer who is the holder of a mechanical contractor's license as the contractor of record.  The buyer shall notify the department in writing of the designation.