Washington Revised Code Title 26. Domestic Relations § 26.09.070. Separation contracts

(1) The parties to a marriage or a domestic partnership, in order to promote the amicable settlement of disputes attendant upon their separation or upon the filing of a petition for dissolution of their marriage or domestic partnership, a decree of legal separation, or declaration of invalidity of their marriage or domestic partnership, may enter into a written separation contract providing for the maintenance of either of them, the disposition of any property owned by both or either of them, the parenting plan and support for their children and for the release of each other from all obligation except that expressed in the contract.

(2) If the parties to such contract elect to live separate and apart without any court decree, they may record such contract and cause notice thereof to be published in a legal newspaper of the county wherein the parties resided prior to their separation.  Recording such contract and publishing notice of the making thereof shall constitute notice to all persons of such separation and of the facts contained in the recorded document.

(3) If either or both of the parties to a separation contract shall at the time of the execution thereof, or at a subsequent time, petition the court for dissolution of their marriage or domestic partnership, for a decree of legal separation, or for a declaration of invalidity of their marriage or domestic partnership, the contract, except for those terms providing for a parenting plan for their children, shall be binding upon the court unless it finds, after considering the economic circumstances of the parties and any other relevant evidence produced by the parties on their own motion or on request of the court, that the separation contract was unfair at the time of its execution.  Child support may be included in the separation contract and shall be reviewed in the subsequent proceeding for compliance with RCW 26.19.020.

(4) If the court in an action for dissolution of marriage or domestic partnership, legal separation, or declaration of invalidity finds that the separation contract was unfair at the time of its execution, it may make orders for the maintenance of either party, the disposition of their property and the discharge of their obligations.

(5) Unless the separation contract provides to the contrary, the agreement shall be set forth in the decree of dissolution, legal separation, or declaration of invalidity, or filed in the action or made an exhibit and incorporated by reference, except that in all cases the terms of the parenting plan shall be set out in the decree, and the parties shall be ordered to comply with its terms.

(6) Terms of the contract set forth or incorporated by reference in the decree may be enforced by all remedies available for the enforcement of a judgment, including contempt, and are enforceable as contract terms.

(7) When the separation contract so provides, the decree may expressly preclude or limit modification of any provision for maintenance set forth in the decree.  Terms of a separation contract pertaining to a parenting plan for the children and, in the absence of express provision to the contrary, terms providing for maintenance set forth or incorporated by reference in the decree are automatically modified by modification of the decree.

(8) If at any time the parties to the separation contract by mutual agreement elect to terminate the separation contract they may do so without formality unless the contract was recorded as in subsection (2) of this section, in which case a statement should be filed terminating the contract.