Beginning 180 days after January 1, 1972, every insurer shall, before using or applying any rate to any kind of insurance coming within the scope of this article, file with the department a copy of the rating plan upon which such rate is based or by which such rate is fixed or determined. The filing required in this section may be made on behalf of such insurer by a rating organization of which such insurer is a member or subscriber. From and after the date of the filing of such rating plans, every insurer shall charge and receive rates fixed or determined in strict conformity therewith, except as in this article otherwise expressly provided.