(1) Any authorized insurer may file a registration statement on behalf of any affiliated insurer or insurers which are required to register under RCW 48.31B.025. A registration statement may include information not required by the act regarding any insurer in the insurance holding company system even if the insurer is not authorized to do business in this state. In lieu of filing a registration statement on Form B, the authorized insurer may file a copy of the registration statement or similar report which it is required to file in its state of domicile, provided:

(a) The statement or report contains substantially similar information required to be furnished on Form B; and

(b) The filing insurer is the principal insurance company in the insurance holding company system.

(2) The question of whether the filing insurer is the principal insurance company in the insurance holding company system is a question of fact and an insurer filing a registration statement or report in lieu of Form B on behalf of an affiliated insurer, must set forth a brief statement of facts which will substantiate the filing insurer's claim that it, in fact, is the principal insurer in the insurance holding company system.

(3) With the prior approval of the commissioner, an unauthorized insurer may follow any of the procedures which could be done by an authorized insurer under subsection (1) of this section.

(4) Any insurer may take advantage of the provisions of RCW 48.31B.025 (8) or (9), without obtaining the prior approval of the commissioner. The commissioner, however, reserves the right to require individual filings if he or she deems the filings necessary in the interest of clarity, ease of administration, or the public good.