Section 626.25 - Use of rates(1) APPROVAL REQUIRED. No insurer writing any insurance specified under s. 626.03 may use a rate, rating plan or classification nor an expense loading not approved by the commissioner.(2) UNFAIR DISCRIMINATION. No insurer writing any insurance specified under s. 626.03 may make or charge any rate which discriminates unfairly between risks or classes, nor discriminates unfairly between risks in the application of rating plans, nor discriminates by granting to any employer insurance against other hazards except in accordance with its rates and rating plans filed and which are in effect for the insurer under ch. 625 nor at less than its legal rates for the insurance if that chapter is inapplicable.