Mo. Rev. Stat. § 379.025
Corporations may be formed for the purpose of doing business mentioned in section 379.010, either on the stock or mutual plan; and every corporation so formed on the mutual plan shall have the word "mutual" affixed to the name which it assumes; and it shall not be lawful for any corporation so formed to do business on any other plan than that upon which it is organized, or for a corporation formed upon the mutual plan in any manner to use its name or to make publication thereof, unless the word "mutual" be affixed thereto in plain letters of the size of the letters in which the balance of the name is printed; and no such corporation shall adopt the name of any existing company or corporation transacting the same kind of business, or a name so similar as to be calculated to mislead the public; and the mutual companies shall not issue policies known as stock policies, or do business as joint stock companies, or upon the joint stock plan; but any mutual company upon a majority vote of its members present at an annual meeting, or at any special meeting called for that purpose after one week's notice by advertisement in one or more newspapers printed and published in the city or county where the chief office of said company is located, may charge and receive for the mutual benefit of all its policyholders cash in payment of premiums on such of its policies as shall be, by a majority vote of such meeting, determined upon.
§ 379.025, RSMo