Mont. Code Ann. § 70-9-806

A holder may deduct from property presumed abandoned a charge imposed by reason of the owner's failure to claim the property within a specified time only if there is a valid and enforceable written contract between the holder and the owner under which the holder may impose the charge and the holder regularly imposes the charge, which is not regularly reversed or otherwise canceled. The amount of the deduction is limited to an amount that is not unconscionable.