A member of or subscriber to a rating organization to whom the provisions of Article 5 of this chapter are applicable may make written application to the department for permission to file a uniform percentage decrease or increase to be applied to the premiums produced by the rating system filed for a kind of insurance or for a class of insurance which is found by the director or his designee to be a proper rating unit for the application of such uniform percentage decrease or increase or for a subdivision of a kind of insurance. The application must specify the basis for the modification and must be accompanied by the data upon which the applicant relies. A copy of the application and data must be sent simultaneously to the rating organization.