A Montana landlord must usually give a tenant 30 days of advance notice if they intend for them to move out without any punitive cause. However, tenants who have committed a lease violation or who have failed to pay rent on time may be asked to move out within 3 days of the infraction. Severe infractions may even justify a 24 hour notice period before an eviction goes into effect.
The information for this answer was found on our Montana Landlord Tenant Rights answers.