Mont. Code § 33-23-302
Any insurer who insures a person licensed in the practice of medicine, as defined in 37-3-102, a dentist, registered nurse, nursing home administrator, registered physical therapist, podiatrist, licensed psychologist, osteopath, chiropractor, pharmacist, optometrist, or veterinarian, licensed under the laws of this state, or a licensed hospital or long-term care facility as the employer of any person identified in this section against liability for error, omission, professional negligence, or performance of services without consent may not cancel or alter the policy insuring the person or increase the premium rates on the policy without first providing the insured 60 days' written notice of the insurer's intention to cancel or alter the policy or increase the premium rates.
§ 33-23-302, MCA