Mont. Code Ann. § 28-10-801
28-10-801 Circumstances that terminate agency
28-10-801 . Circumstances that terminate agency. An agency is terminated as to every person having notice of the termination by:
(1) the expiration of the agency's term;
(2) the extinction of the agency' subject;
(3) the death of the agent;
(4) the agent's renunciation of the agency; or
(5) the incapacity of the agent to act as an agent.