Wash. Rev. Code § 26.16.090
A spouse or domestic partner may make and execute a letter of attorney to his or her spouse or domestic partner authorizing the sale or other disposition of his or her community interest or estate in the community property and as such attorney-in-fact to sign the name of such spouse or such domestic partner to any deed, conveyance, mortgage, lease or other encumbrance or to any instrument necessary to be executed by which the property conveyed or transferred shall be released from any claim as community property. And either spouse or either domestic partner may make and execute a letter of attorney to any third person to join with the other in the conveyance of any interest either in separate real estate of either, or in the community estate held by such spouse or such domestic partner in any real property. And both spouses or both domestic partners owning community property may jointly execute a power of attorney to a third person authorizing the sale, encumbrance or other disposition of community real property, and so execute the necessary conveyance or transfer of said real estate.
RCW 26.16.090
Part headings not law-Severability-2008 c 6: See RCW 26.60.900 and 26.60.901.