Washington Revised Code Title 48. Insurance § 48.66.050. Policy or certificate provisions prohibited by rule--Waivers restricted

(1) The insurance commissioner may issue reasonable rules that specify prohibited policy provisions not otherwise specifically authorized by statute which, in the opinion of the commissioner, are unfair, unjust, or unfairly discriminatory to any person insured or proposed to be insured under a medicare supplement insurance policy or certificate.

(2) No medicare supplement insurance policy may use waivers to exclude, limit, or reduce coverage or benefits for specifically named or described preexisting diseases or physical conditions.