A tenant who vacates a dwelling unit during the term of a tenancy may not allow the possession of the property to be transferred to a third person or sublet the property unless the landlord or the landlord's agent has consented in writing.
Mont. Code Ann. § 70-24-305, under Rights and Duties of the Parties.
Mont. Code Ann. § 70-24-305
A tenant who vacates a dwelling unit during the term of a tenancy may not allow the possession of the property to be transferred to a third person or sublet the property unless the landlord or the landlord's agent has consented in writing.