(a) No advertisement may use the word "dividends" or similar words or illustrations in such a manner as to state or to imply that future dividends are guaranteed or certain to occur.(b) The word "dividends" includes every return of premium and payment to policyholders on a particular policy that is predicated on the financial performance or earnings of the insurer, but does not include the return of premium under a nondiscretionary provision or endorsement in a policy clearly providing for the payment under a rating plan approved or promulgated by the Texas Department of Insurance.