How to modify a child custody order or parenting plan in Washington

Sources last checked 7 November 2026. Information only, not legal advice. This page rests on the text of the Revised Code of Washington 26.09.260 (modification of a parenting plan or custody decree) and 26.09.270 (affidavit and adequate cause), as published by the Washington State Legislature on app.leg.wa.gov. Washington’s statutes use “parenting plan” and “residential schedule”. Read what we could not confirm below.

Washington divorce kit Child custody in Washington Modifying child support and spousal support in Washington After your divorce: changing a support or custody order

The short version

Washington sets a high general rule, then carves out lighter routes. Under RCW 26.09.260(1) the court may not change a parenting plan unless it finds, from facts that arose since the plan or were unknown to the court, that “a substantial change has occurred in the circumstances of the child” or the other parent, and that the change is “necessary to serve the best interests of the child”. The court keeps the existing residential schedule unless one of four listed grounds applies. Smaller changes to the schedule, and changes to non-residential terms, have easier tests. Everything starts with an affidavit and an “adequate cause” screening. For support, see modifying child support and spousal support in Washington.

First hurdle: affidavit and adequate cause, RCW 26.09.270

Affidavit. A party seeking modification submits with the motion an affidavit setting out the facts that support it, and gives notice and a copy to the other parties, who may file opposing affidavits.
Screening. “The court shall deny the motion unless it finds that adequate cause” for a hearing is shown by the affidavits. If it does, the court sets a hearing on an order to show cause.
Relocation exception. No adequate cause hearing is required while a relocation request is being pursued (see below).

The general test and the four exceptions, RCW 26.09.260

General rule. The court must find a substantial change in the circumstances of the child or the nonmoving party, based on new or previously unknown facts, and that the modification is “necessary to serve the best interests of the child”.
Default. The court will “retain the residential schedule established by the decree or parenting plan” unless:
(a) Agreement. “The parents agree to the modification”.
(b) Integration. The child has been integrated into the petitioner’s family, with the other parent’s consent, in substantial deviation from the plan.
(c) Detriment. The child’s present environment is detrimental to the child’s physical, mental or emotional health, and the harm from a change is outweighed by the advantage of a change.
(d) Contempt or interference. The nonmoving parent was found in contempt at least twice within three years for not following the residential time provisions, or was convicted of custodial interference in the first or second degree. A conviction of that kind is also a substantial change.
Fees for bad faith. If a motion to modify is brought in bad faith, the court shall assess the other parent’s attorney fees and court costs against the moving party.

Lighter routes

Minor schedule changes, subsection (5). A substantial change in circumstances is still needed, but the court need not apply the four grounds above if the change leaves the child’s majority residence alone and either does not exceed “twenty-four full days in a calendar year”, or follows the other parent’s move or an involuntary work schedule change that makes the schedule impractical.
Added time up to 90 overnights. If the plan does not give reasonable time to the parent the child does not live with most of the time, the court may increase it, up to a total that does not exceed “ninety overnights per year”, if that is in the child’s best interests. Limits apply if you used this route in the last 24 months, if your time is restricted under RCW 26.09.191 or 26.09.192, or if you have not completed required evaluations, treatment or classes.
Non-residential terms, subsection (10). Substantial change in circumstances of either parent or the child, plus the child’s best interest, without the four grounds. Decision-making and similar terms fall here.
Unused time. If the parent the child does not live with most of the time “voluntarily fails to exercise residential time for an extended period” of one year or more, the court may adjust the plan.
Restricting contact. The court may reduce or restrict contact if it serves and protects the child’s best interests under the criteria in RCW 26.09.191 and 26.09.192.

If a parent plans to move

Modification with a relocation. A parent objecting to a relocation, or the relocating person with a revised schedule, may petition to modify the plan, including the child’s majority residence, “without a showing of adequate cause other than the proposed relocation itself”.
Order of decisions. The court first decides whether to permit or restrain the relocation using RCW 26.09.405 through 26.09.560, then decides what modification to make. We did not read those sections.

Military service

No permanent change from duty alone. The effect of a parent’s military duties on parenting functions “shall not, by itself, be a substantial change” justifying a permanent modification.
Temporary orders. The statute has specific rules for deployment, including ending temporary custody orders soon after the parent returns and letting the court delegate time to a family member. We did not summarize every step.

Forms and filing

Form. We did not read the Washington Courts forms for a petition to modify a parenting plan or custody decree. Ask the superior court clerk or the Washington Courts forms page for current forms.
Where to file. Normally the superior court that entered the plan, subject to the jurisdiction act. See child custody in Washington.

What we could not confirm

Case law. We read no Washington appellate decision, so we cannot say how courts apply “substantial change”, adequate cause or the four grounds.
Relocation statutes. RCW 26.09.405 to 26.09.560 (notice, objection, presumptions) were not read.
Best-interest factors. We did not read the residential provisions (RCW 26.09.187) or the restrictions in RCW 26.09.191 and 26.09.192.
Procedure. We did not read mediation or dispute resolution requirements, filing fees, fee waivers or local rules.

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