such insurer shall be required to file only the group certificate and notice of proposed insurance delivered or issued for delivery in this state as specified in sections 6(b) and 6(d) of this chapter, and such forms shall be approved by the commissioner if they conform with the requirements specified in sections 6(b) and 6(d) and if the schedules of premium rates applicable to the insurance evidenced by such certificate or notice are not in excess of the insurer's schedules of premium rates on file with the commissioner; provided, however, that the premium rate in effect on group policies existing on July 6, 1961, may be continued until the first policy anniversary date following the date this section becomes operative as provided in section 12 of this chapter.
IC 27-8-4-7