(1) Unless a vote of a greater proportion of directors or shares is required by its articles of incorporation, amendments to the articles of incorporation of a domestic insurer or a domestic insurance holding corporation shall be made by a majority vote of its board of directors and the vote or written assent of a majority of its voting capital stock, or two-thirds of the members (if a mutual insurer) voting at a valid meeting of members.
(2) The president and secretary of the insurer shall, under the corporate seal, certify the amendment in duplicate, and file both copies in the office of the commissioner as required under this code for original articles of incorporation. Thereupon, subject to the requirements of RCW
48.08.010 relative to increase of capital stock of a stock insurer, the amendment shall become effective.