Mont. Code Ann. § 35-4-403

A professional corporation, domestic or foreign, may render professional services in this state only through natural persons permitted to render the services in this state. However, nothing in this chapter requires any person employed by a professional corporation to be licensed to perform services for which a license is not otherwise required or prohibits the rendering of professional services by a licensed natural person acting in an individual capacity, even if the person is a shareholder, director, officer, employee, or agent of a professional corporation, domestic or foreign.