After July 1, 1935, every insurance company authorized to effect worker's compensation insurance in this state shall be a member of the worker's compensation rating bureau of Indiana. The bureau shall be composed of all insurance companies lawfully engaged on July 1, 1935, wholly or in part in making worker's compensation insurance in Indiana or who shall after July 1, 1935, be issued a certificate of authority to make worker's compensation insurance in this state.
IC 27-7-2-3