(1) Subject to rules and regulations which have been approved by the commissioner as reasonable, each rating organization shall permit any insurer to subscribe to its rating services for any kind of insurance or subdivision thereof, for which it is authorized to act as a rating organization, subject to subsection (2) of RCW 48.19.050.

(2) Notice of proposed changes in such rules and regulations shall be given to each subscriber.

(3) An insurer shall not concurrently be a subscriber to the services of more than one rating organization as to the same subdivision, class of risk or part or combination of a kind of insurance.

(4) As to fire insurance under standard form fire policies, an insurer may not concurrently be a subscriber to the services of more than one rating organization except as provided in subsection (2) of RCW 48.19.050.