The question whether a doctor of medicine renders services in an employment relationship
            is difficult to resolve. Where a doctor performs medical services for an industrial
            firm, in addition to a private practice, there may or may not be an employment relationship.
            In other cases, the circumstances under which a doctor enters into a work agreement
            with a hospital or medical group may raise a question as to the validity of an alleged
            employer-employee relationship.
         
         Doctors of medicine engaged in their own practices were first covered under Social
            Security effective with taxable years ending on and after December 31, 1965. Many
            doctors have private practices exclusively. Some doctors do not have private practices,
            but devote their full time to performing medical services for others, such as government
            organizations, industrial employers, etc. In such instances, the doctors usually render
            the services in an employment relationship and the services are covered on the same
            basis as other employment.