Washington Revised Code Title 11. Probate and Trust Law § 11.11.030. Waiver of right to dispose of a nonprobate asset under will--Revocation of waiver

An owner may waive the right to dispose of a specific nonprobate asset by will under this chapter, with or without consideration, by a written instrument signed by the owner and delivered to the financial institution or other third party, including but not limited to signature cards or deposit agreements. The waiver is revocable by written instrument delivered to the financial institution or other third party unless the owner has stated that the waiver is to be irrevocable.