Mont. Code Ann. § 27-2-301

Where a right exists but a demand is necessary to entitle a person to maintain an action, the time within which the action must be commenced must be computed from the time when the demand is made, except where the right grows out of the receipt or detention of money or property by an agent, trustee, attorney, or other person acting in a fiduciary capacity, the time must be computed from the time when the person having the right to make the demand has actual knowledge of the facts upon which that right depends.