MI HB4120

Exempts domestic air carriers from use tax on aircraft with a maximum certificated takeoff weight of at least 6,000 pounds used solely for transporting air cargo, passengers, or both

Expands the tax exemption on parts and materials affixed to aircraft by removing previous conditions requiring the aircraft to leave the state within 15 days and not be based or registered in Michigan

Maintains exemption for aircraft sales in Michigan if the aircraft leaves within 15 days after sale and completion of any associated work, and is not based or registered in the state afterward

Adds a formal definition of "aircraft" as an aerial vehicle used in aviation, excluding unmanned aerial vehicles

Takes effect 90 days after enactment, contingent on passage of a companion Senate or House bill, with legislative intent to appropriate funds to compensate the state school aid fund for any revenue loss