Mont. Code Ann. § 70-33-425

If there is noncompliance by the tenant with 70-33-321 affecting health and safety that can be remedied by repair, replacement of a damaged item, or cleaning and the tenant fails to comply as promptly as conditions require in case of emergency or within 14 days after written notice by the landlord specifying the breach and requesting that the tenant remedy the breach within that period of time, the landlord may enter the lot and cause the work to be done in a competent manner and submit an itemized bill for the actual and reasonable cost, the fair and reasonable cost, or the fair and reasonable value of the work as rent on the next date rent is due or, if the rental agreement has terminated, for immediate payment.