How to modify child support or spousal maintenance in Washington

Sources last checked: 3 November 2026. Information only, not legal advice. The Cusp is not a law firm.

Washington divorce kitHow child support is calculatedAlimony in WashingtonLegal aid in WashingtonAfter your divorce: changing an order

The short version

Washington’s word for spousal support is “maintenance”. Both child support and maintenance are changed under one statute, RCW 26.09.170. For child support, a proceeding starts when you file a petition and child support worksheets, and the petition must be on the form the courts’ administrator prescribes. That is the courts’ FL Modify 501, Petition to Modify Child Support (mandatory form, 01/2022). If at least 24 months have passed and the only reasons are changed incomes or a changed economic table, there is a shorter route, the Motion to Adjust Child Support Order (FL Modify 521). A change reaches back only to the date of the petition or motion. We found no statewide court form for changing maintenance (see “What we could not confirm” below).

The test for child support

Wording below is a plain-language summary of the Revised Code of Washington as we read it on 3 November 2026, with short quotations.

  • The general test, RCW 26.09.170(1): support or maintenance may be modified “only upon a showing of a substantial change of circumstances”, except as the section says otherwise.
  • Child support, any time, 170(5): a party to a child support order may petition on “substantially changed circumstances at any time”. The “voluntary unemployment or voluntary underemployment of the person required to pay support” is “not a substantial change of circumstances” by itself.
  • One year or more after the order, without showing a change, 170(8): if the order in practice works a “severe economic hardship on either party or the child”, if a child is still in high school and there is a “need to extend support beyond the eighteenth birthday” to finish, or to “add an automatic adjustment of support provision”.
  • Adjustment after 24 months, 170(9): once 24 months have passed from the order or the last adjustment or modification, “the order may be adjusted without a showing of substantially changed circumstances” because of changes in either parent’s income, or changes in the economic table or standards in chapter 26.19 RCW. “Either party may initiate the adjustment by filing a motion and child support worksheets”. If the change is more than 30 percent and would cause significant hardship, the court may “implement the change in two equal increments”, the second six months later.
  • Jail or prison, 170(6) and (7): an order can be modified at any time to add language on “abatement to ten dollars per month per order” while the payer is incarcerated. A petition for that must be filed while the payer is currently confined for at least six months. No substantial change is needed to modify an order after the payer is released, as RCW 26.09.320(3)(d) provides. We did not read RCW 26.09.320.
  • State agency, 170(10) and (11): the Department of Social and Health Services (DSHS) “may file an action to modify or adjust an order of child support” in several situations, including where it has determined that a support order is “at least fifteen percent above or below the appropriate child support amount” and public assistance is being paid, or in a case without assistance where a party has asked for a review and its review criteria are met.
  • When support ends, 170(3): unless agreed in writing or the decree says otherwise, provisions for the support of a child “are terminated by emancipation of the child” or by the death of the person required to pay.
  • Update coming 1 April 2027: the same page shows a second version of section 170, marked “Effective April 1, 2027”, from 2025 c 272. It adds a parallel to the incarceration rule for a payer in “court-ordered behavioral health treatment”, with abatement to “$50 per month per child due to incapacitation” under RCW 26.09.345. We did not read RCW 26.09.345. Until then the version above applies.

The test for maintenance

  • Same section, same standard: maintenance may be modified “only upon a showing of a substantial change of circumstances” (RCW 26.09.170(1)(b)). We found no separate procedure statute for maintenance (see below).
  • How far back, 170(1)(a): a change applies “installments accruing subsequent to the petition for modification” or motion for adjustment. In plain terms, payments that came due before you file are not changed by the court under this section.
  • What ends it by itself, 170(2): unless agreed in writing or expressly provided in the decree, the “obligation to pay future maintenance is terminated” on the death of either party or the remarriage of the recipient. The same applies to the “registration of a new domestic partnership of the party receiving maintenance”.
  • An agreement can lock it, RCW 26.09.070(7): when the separation contract so provides, the decree “may expressly preclude or limit modification of any provision for maintenance”.
  • Property is different: the property provisions of a decree “may not be revoked or modified” unless the court finds conditions that justify reopening the judgment, 170(1).

Forms for child support

The Washington Courts forms page lists these under “Modification of Child Support”. The petition says it is a mandatory form and tells you to “Check your county’s Local Court Rules for other forms and information”, so your county may require more.

Maintenance: the Courts’ forms page uses the word “maintenance” nowhere, and its modification forms are all for child support or parenting plans.

Notice, service and hearing (child support)

  • Starting the case, RCW 26.09.175(1): a modification proceeding “shall commence with the filing of a petition and worksheets”.
  • Which case number: the petition says that if you file in the same case number as the current order, the person listed as Petitioner there “will stay Petitioner”, even if they are not the one asking to modify now.
  • Service, 175(2): the petitioner serves the summons, petition and worksheets. If this is the first action filed in this state, “service shall be made by personal service”. If the decree was entered in Washington, service is “by personal service or by any form of mail requiring a return receipt”, and proof of service is filed. If support has been assigned to the state, the attorney general (or the county prosecutor, in some counties) must also be served.
  • The other side’s response, 175(4): the answer and worksheets are due “within twenty days after service of the petition”, or sixty days if served out of state. A missed answer “shall result in entry of a default judgment” for the petitioner. The summons form says the same, with 60 days also for service in jail, detention or prison.
  • Hearing, 175(5) and (6): after responses are filed, either party may schedule a hearing. The matter is “heard by the court on affidavits, the petition, answer, and worksheets only”, unless the parties agree to arbitration or the presiding judge allows oral testimony.
  • Asking for testimony, 175(7): a motion for oral testimony is due “not later than ten days after the time of notice of hearing”, with affidavits showing why it is needed. If testimony is required, 175(8) says the court must allow it by telephone or other electronic means unless good cause is shown.

Before you file

  • Court staff cannot give legal advice. See legal aid in Washington for free or low-cost help, or the Washington divorce kit for the wider process.
  • Because a change reaches back only to the petition or motion, ask the clerk how to file in your county as soon as you decide to move.
  • Fee we can state: RCW 26.09.175(1) sets a “fee of twenty dollars for the filing of a petition” for modification of a dissolution. That is the statute’s own figure. We did not read any county fee schedule, so ask the clerk for the total you will owe, and ask about the fee-waiver motion above if you cannot afford it.
  • Lawyer’s fees: under RCW 26.09.140 the court may, after considering both parties’ resources, order a party to pay “reasonable attorneys’ fees or other professional fees” in “enforcement or modification proceedings after entry of judgment”.
  • Check the revision date printed on each form before you file. The petition is dated 01/2022 and the summons 09/2026.
  • Child support amounts follow the state schedule. See how child support is calculated in Washington, alimony in Washington, and after your divorce: changing an order.

What we could not confirm

  • A statewide form or procedure for changing maintenance. RCW 26.09.175 and the FL Modify forms are written for child support. The Courts’ family law forms page lists no maintenance modification form. We did not read the civil rules on motions, so we do not say how a maintenance request is brought or served.
  • The official web version of the Code. The legislature’s RCW site (app.leg.wa.gov) tells automated readers not to crawl it, so we did not use it. We read the legislature’s own file copies of the sections on its law-files server.
  • The Division of Child Support (DSHS) review process. We read what RCW 26.09.170 and .175 say about DSHS, but not DSHS’s own pages, its forms, or how long a review takes.
  • County rules and fees. We did not read any county’s local court rules, clerk fee schedules or surcharges.
  • Other statutes. We did not read RCW 26.09.320 (incarceration), 26.09.345 (incapacity), 26.09.100 (automatic adjustment), or chapter 26.19 RCW (the schedule, deviations and limits).
  • How courts decide. We read no court decisions, so we do not say what counts as a “substantial change” in practice.
  • Past-due support. We read only the rule that a change reaches back to the petition or motion. We did not read the rules on collecting or forgiving arrears.

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Sources