Wash. Rev. Code § 48.44.430
Upon application by a subscriber, a rider shall be canceled if at least five years after its issuance, no health care services have been received by the subscriber during that time for the condition specified in the rider, and a physician, selected by the carrier for that purpose, agrees in writing to the full medical recovery of the subscriber from that condition, such agreement not to be unreasonably withheld. The option of the subscriber to apply for cancellation shall be disclosed on the face of the rider in clear and conspicuous language.
For purposes of this section, a rider is a legal document that modifies a contract to exclude, limit, or reduce coverage or benefits for specifically named or described preexisting diseases or physical conditions.
RCW 48.44.430