Mont. Code Ann. § 7-7-2106

The county treasurer, upon the production of any original bond, warrant, or coupon by the lawful owner or holder, shall assign by endorsement and deliver to the owner or holder the surety bond mentioned in 7-7-2104. The owner or holder may maintain an action upon the surety bond for the recovery of any money paid upon the duplicate, but the delivery of the surety bond does not relieve or exonerate the county from the payment of the amount specified in the bond upon a demand and refusal of the sureties named in the indemnifying surety bond to pay the amount.