Start with Wash. Rev. Code ch. 26.19. In Washington, Washington uses the Income shares and measures income as net income. Washington’s economic table uses combined monthly net income to determine a basic support obligation allocated by income share. The worksheets also address health insurance, daycare, and the fifty-percent limitation in some low-income situations. That is the question this guide answers for how child support is calculated. Support generally ends when Support generally continues until 18, or longer for secondary education under post-secondary support rules if ordered. Modification: Substantial change of circumstances; a significant variance from the standard calculation often supports modification.
Statutory framework and guideline model
Washington's child support system is built around Wash. Rev. Code ch. 26.19. Under the income shares, Washington’s economic table uses combined monthly net income to determine a basic support obligation allocated by income share. The worksheets also address health insurance, daycare, and the fifty-percent limitation in some low-income situations.
Federal law requires every state to maintain presumptive guidelines and to review them at least every four years (42 U.S.C. § 667). Confirm the latest Washington schedule or worksheet before relying on any online calculator.
How child support is calculated in Washington
- Identify each parent's guideline income using net income as defined in Wash. Rev. Code ch. 26.19 and the accompanying worksheets or administrative rules.
- Apply the income shares — whether that means a combined-income schedule, an obligor percentage table, or a Melson-style self-support reserve plus primary obligation.
- Allocate add-ons such as health insurance premiums, unreimbursed medical expenses, and work-related child care according to Washington practice.
- Consider parenting time adjustments where the guidelines or case law authorize a credit or shared-custody formula.
- Test for deviation if a strict guideline result would be unjust or inappropriate on the record.
Online calculators can illustrate ranges, but only the controlling statute, guidelines, and court findings produce an enforceable order.
How the Washington rule applies
Apply the Washington authorities in order. The facts are simplified so the statute and the standard are visible.
Two parents in Washington need a presumptive child-support figure and may have facts that justify a departure.
- Measure guideline income as net income under Wash. Rev. Code ch. 26.19.
- Apply the Income shares: Washington’s economic table uses combined monthly net income to determine a basic support obligation allocated by income share. The worksheets also address health insurance, daycare, and the fifty-percent limitation in some low-income situations.
- Test deviation: Deviation standards in RCW 26.19.075 cover children from other relationships, wealth, and other inequities.
- If circumstances later change: Substantial change of circumstances; a significant variance from the standard calculation often supports modification.
The enforceable number is the Washington guideline result under Wash. Rev. Code ch. 26.19, plus any deviation findings. Division of Child Support enforces via withholding, intercepts, and contempt.
Deviation from the guidelines
Deviation standards in RCW 26.19.075 cover children from other relationships, wealth, and other inequities.
When a court departs from the presumptive amount, Washington practice generally requires findings that explain why the guideline figure is unjust or inappropriate and what amount better serves the child's needs. Those findings matter on appeal and in later modification proceedings.
Modification of child support
Substantial change of circumstances; a significant variance from the standard calculation often supports modification.
A parent seeking a change typically must show that circumstances after the prior order make the existing award inequitable. Common triggers include job loss, substantial income changes, a new parenting-time schedule, emancipation of a child, or extraordinary medical needs. Retroactivity and temporary relief rules are statute-specific — check Wash. Rev. Code ch. 26.19 and local family-division procedures.
Enforcement in Washington
Division of Child Support enforces via withholding, intercepts, and contempt.
Interstate cases often implicate UIFSA. Income withholding, contempt, license suspension, and tax-refund intercept remain core tools nationwide, but the Washington child support agency and clerk of court procedures control day-to-day collection.
When child support ends
In Washington, Support generally continues until 18, or longer for secondary education under post-secondary support rules if ordered. Orders may extend for disability, secondary education, or other statutory grounds where the statute allows. Always read the judgment language — agreed orders sometimes set a different end date or require a notice of emancipation.
Case law: how Washington courts apply the guidelines
The opinions below are in the LawDiver corpus. Each block quote is taken from the opinion text so you can jump from this guide into the full decision.
In Re Marriage of Dodd
In Re Marriage of Dodd, 86 P.3d 801 (2004)
…nt. BROWN, C.J. David Dodd appeals a Spokane Superior Court child support modification order entered in favor of Karen Dodd based upon income imputed to Mr. Dodd under RCW 26.19.071(6). The issue is whether the trial court properly revised its court commissioner's order, which also imputed income to Mr. Dodd, but at a lower amount based upon what the commissioner believed Mr. D…
In Re Marriage of Dodd is worth reading on Washington child support because the court put the point in its own words: "BROWN, C.J. David Dodd appeals a Spokane Superior Court child support modification order entered in favor of Karen Dodd based upon income imputed to Mr. Dodd under RCW 26.19.071(6)." Use that passage as the starting point, then read the facts that precede it.
In Re Marriage of Scanlon and Witrak
In Re Marriage of Scanlon and Witrak, 34 P.3d 877 (2001)
…BAKER, J. Barry Scanlon appeals an order on modification of child support that increased his child support obligation, allocated long distance transportation expenses and tax exemptions, and ordered postsecondary educational support, but failed to address his request for attorney fees. We reverse. I Barry Scanlon and Bonnie Witrak, both physicians, dissolved their marriage in 1…
On child support, In Re Marriage of Scanlon and Witrak speaks to the Washington dispute in this passage: "R, J. Barry Scanlon appeals an order on modification of child support that increased his child support obligation, allocated long distance transportation expenses and tax exemptions, and ordered postsecondary educational support, but failed to address his request for attorney fees." The surrounding opinion shows how the court applied that language to the record.
In the Matter of the Marriage of David F. Nelson, Respondent, and Diane K. Nelson, Appellant
…denying her request for attorney fees. Finding that in her child support enforcement action Ms. Grossman was a prevailing party as that term is used in RCW 26.18.160, and finding the record incomplete regarding her claim for attorney fees in her modification action, we reverse and remand to the trial court. I Diane Grossman and David Nelson are former husband and wife. Pursuan…
Practitioners open In the Matter of the Marriage of David F. Nelson, Respondent, and Diane K. Nelson, Appellant when Washington child support turns on the distinction in this sentence: "Finding that in her child support enforcement action Ms. Grossman was a prevailing party as that term is used in RCW 26.18.160, and finding the record incomplete regarding her claim for attorney fees in her modification action, we reverse and remand to the trial court." Do not lift it out of the facts the court was deciding.
In Re Marriage of Didier
In Re Marriage of Didier, 140 P.3d 607 (2006)
…n order holding him in contempt for failing to pay past due child support. Michael[1] maintains that (1) the commissioner erred in imputing his income to calculate the child support award; (2) the child support obligations violate his right to free exercise of religion; and (3) the contempt sanction violated his constitutional rights because it was punitive in nature. We uphold…
Washington opinions such as In Re Marriage of Didier are cited where child support is disputed. The court stated: "n order holding him in contempt for failing to pay past due child support. Michael[1] maintains that (1) the commissioner erred in imputing his income to calculate the child support award; (2) the child support obligations violate his right to free exercise of religion; and (3) t" That is the language to brief; the rest of the decision supplies the procedural posture.
In Re Marriage of Daubert
In Re Marriage of Daubert, 99 P.3d 401 (2004)
…chard Johnson appeals the trial court's modification of his child support payments on three grounds. First, the trial court failed to enter separate findings of fact and conclusions of law to support the increased support amount. Second, the "scant findings" in the Order of Child Support are not supported by the evidence. Finally, the court's decision was based on untenable gro…
Practitioners open In Re Marriage of Daubert when Washington child support turns on the distinction in this sentence: "Johnson appeals the trial court's modification of his child support payments on three grounds. First, the trial court failed to enter separate findings of fact and conclusions of law to support the increased support amount." Do not lift it out of the facts the court was deciding.
In Re Marriage Holmes
In Re Marriage Holmes, 117 P.3d 370 (2005)
…ial court decisions entering a parenting plan and modifying child support. A provision in the parenting plan granting the guardian ad litem (GAL) authority to determine when to reinstate the original return time in the residential schedule was a proper temporary order and not a modification of the parenting plan. In addition, because the child now resides with the father a majo…
Washington opinions such as In Re Marriage Holmes are cited where child support is disputed. The court stated: "A provision in the parenting plan granting the guardian ad litem (GAL) authority to determine when to reinstate the original return time in the residential schedule was a proper temporary order and not a modification of the parenting plan." That is the language to brief; the rest of the decision supplies the procedural posture.
In the Matter of the Marriage of Joy Newell, and LaFrank Newell
In the Matter of the Marriage of Joy Newell, and LaFrank Newell, 117 Wash. App. 711 (2003)
…e percentage share of income. We conclude that although the child support schedule for postsecondary education support is advisory and not mandatory, the trial court must accurately calculate the parties’ incomes and the presumptive proportional percentage share of income before deciding how to allocate postsecondary education expenses between the parents. We reverse and remand…
Practitioners open In the Matter of the Marriage of Joy Newell, and LaFrank Newell when Washington child support turns on the distinction in this sentence: "e percentage share of income. We conclude that although the child support schedule for postsecondary education support is advisory and not mandatory, the trial court must accurately calculate the parties’ incomes and the presumptive proportional percentage share of income before" Do not lift it out of the facts the court was deciding.
In the Matter of the Marriage of Karen E. Gilbert, Respondent, and David A. Gilbert, Appellant
…s an order entered under RCW 26.19.065 requiring him to pay child support at the statutory minimum amount of $25 per child per month. He contends that because federal law prohibits states from enacting child support schedules that permit no rebuttal of the amount awarded, the provision of RCW 26.19.065(2) mandating a minimum support obligation of $25 per child per month violate…
In the Matter of the Marriage of Karen E. Gilbert, Respondent, and David A. Gilbert, Appellant is worth reading on Washington child support because the court put the point in its own words: "RCW 26.19.065 requiring him to pay child support at the statutory minimum amount of $25 per child per month. He contends that because federal law prohibits states from enacting child support schedules that permit no rebuttal of the amount awarded, the provision of RCW 26.19." Use that passage as the starting point, then read the facts that precede it.
Practical checklist for Washington child support matters
- Gather recent pay stubs, tax returns, and proof of health insurance / child-care costs.
- Complete the current Washington worksheet or financial affidavit required by the local court.
- Document parenting-time overnights if a shared-custody adjustment may apply.
- Flag facts that could support deviation (special needs, travel costs, high income, other children).
- Search LawDiver for recent Washington appellate decisions before mediation or trial.
Key takeaways
- Washington follows the Income shares model for presumptive child support.
- Income is generally measured using net income, then allocated under Wash. Rev. Code ch. 26.19.
- Guideline amounts are presumptive, not automatic — courts may deviate when the facts justify it.
- Support generally continues until 18, or longer for secondary education under post-secondary support rules if ordered.
- Either parent can seek modification when substantial change of circumstances; a significant variance from the standard calculation often supports modification..
- Read the companion guide: Washington alimony / spousal maintenance.
Frequently asked questions
How is child support calculated in Washington?
Washington uses the income shares under Wash. Rev. Code ch. 26.19. Courts start with net income, apply the guideline schedule or percentage, allocate add-ons, and may deviate with findings when the presumptive amount is unjust.
What income counts for Washington child support?
Guideline income generally tracks net income as defined by Wash. Rev. Code ch. 26.19 and the worksheets. Wages, self-employment income, bonuses, and certain benefits are commonly included; exact deductions and exclusions are statute-specific.
Can Washington courts order more or less than the guideline amount?
Yes. Guideline support is presumptive. Judges may deviate when the record shows the guideline result is unjust or inappropriate, typically with written findings explaining the departure.
How do I modify a Washington child support order?
Substantial change of circumstances; a significant variance from the standard calculation often supports modification. File in the court with continuing jurisdiction (or follow UIFSA for interstate cases) and support the request with current financial evidence.
When does child support end in Washington?
Support generally continues until 18, or longer for secondary education under post-secondary support rules if ordered. Confirm any disability, educational, or agreed extensions in your particular order.
Where can I research Washington child support case law?
Use LawDiver search scoped to Washington, or open the opinions linked in this guide. Companion reading: Washington spousal maintenance guide.
Disclaimer
This guide is general legal information about Washington child support, not legal advice. Statutes, guidelines, and case law change. Confirm the current text of Wash. Rev. Code ch. 26.19 and consult a licensed Washington family-law attorney about your facts.