Mont. Code § 7-2-2752
It is intended by the provisions of this part that no part of the indebtedness of an abandoned and abolished county shall be assumed by, become an obligation of, or be paid by a county to which the territory of the abandoned and abolished county is attached and made a part, but that all money in all funds of an abandoned and abolished county at the time it ceases to exist and all money thereafter received by such funds from the payment of delinquent taxes and unpaid licenses and from all other sources owing to such county at the time it ceased to exist and all money received from the rental or sale of the property owned by such county shall be used for the payment of its indebtedness existing at the time it ceased to exist and the cost and expense of attaching its territory to and making it a part of any adjoining county. Such county to which any part of its territory is attached and made a part shall receive only such balance of any such money as may remain after all of the indebtedness and cost are fully paid.
§ 7-2-2752, MCA