- Jason Strouf, Custer County Commissioner, MACo President (09/2021-09/2022)
- Roman Zylawy, Mineral County Commissioner, MACo 1st Vice President (09/2021-09/2022)
- Ross Butcher, Fergus County Commissioner, MACo 2nd Vice President (09/2021-09/2022)
- Doug Martens, Rosebud County Commissioner, MACo Immediate Past President (09/2021-09/2022)
- Mike McGinley, Beaverhead County Commissioner, MACo Fiscal Officer (09/2021-09/2023 — FO is a 2-year term)
- Denis Pitman, Yellowstone County Commissioner, Urban Counties Representative (09/2021-09/2022)
- Eric Bryson, MACo Executive Director, Trust Secretary (Non-Voting)
The Board of Trustees consists of the MACo Executive Committee (President, 1st Vice President, 2nd Vice President, Immediate Past President, Fiscal Officer, and Urban Counties Representative).