After May 31, 1978, an insurer may file with the department a written notice of its election to comply with the provisions of this article after a specified date before May 31, 1980. After the filing of the notice, upon the specified date, which is the operative date of this article for the insurer, this article becomes operative with respect to annuity contracts thereafter issued by the insurer. If an insurer makes no election, the operative date of this article for the insurer is May 31, 1980.