RCW 30A.22.150

Financial institutions may make payments of funds on deposit in an account established by a depositor who is a minor or incompetent without regard to whether it has actual knowledge of the minority or incompetency of the depositor unless the branch of the financial institution at which the account is maintained has received written notice to withhold payment to the minor or incompetent by the guardian of his or her estate and had a reasonable opportunity to act upon the notice.