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WashingtonIncome Shares ModelWashington GuidelinesFree · 2026

Washington Child Support Calculator 2026

Estimate child support under RCW 26.19.020 using the Income Shares Model. Considers both parents' income, custody time, and additional expenses.

1Enter both parents' gross monthly income
2Set number of children & custody %
3Add health insurance, childcare, extras

By Sammy S. · Founder · AuthorUpdated for 2026

Estimates only — not legal advice. Courts make final determinations. Consult a family law attorney.

Child Support Calculator

Enter details to estimate payments

1Location

State-specific guidelines apply. Calculations may vary by state.

2Number of Children
child
3Gross Monthly Income
A
$
B
$
4Parenting Time
A70%·B30%
%

Parent A's custody %. Parent B calculated automatically.

5Who Pays Support?

Washington · Income Shares

Estimated Child Support

$131
per month
$1,566
per year
Parent B pays·1 child·4.3% of payer income·Combined $8,000/mo

Weekly

$30

Biweekly

$60

Monthly

$131

Annual

$1,566

Income & custody split

Parent A — $5,000/mo62.5%
Parent B — $3,000/mo37.5%
Parent A custodyParent B custody
70%30%

Calculation breakdown

Base Support$131
Monthly Support$131
Typical range$117 – $144

Guideline: RCW 26.19.020

Updated: 2026 · Official source

Recalculate if income changes by about 15–20% or more.

Shared custody can lower the paying parent's obligation.

This is an estimate only — courts make the final order.

Child support is generally not tax deductible or taxable income.

Add-ons like childcare, insurance, or medical costs can raise the total.

High-income cases above guideline caps often use court discretion.

Verify amounts with the official calculator for your location.

Consider a family law professional before relying on any estimate.

Estimate only — not a court order.

Washington child support — key facts

  • FormulaIncome Shares Model
  • Guideline referenceRCW 26.19.020
  • Guidelines last updated2026

Example: $5,000 + $3,000 income, 2 kids, 70/30 custody

Combined income$8,000
Parent A share62.5%
Parent B share37.5%
Monthly support$183
Annual support$2,196

Estimate only. Excludes health insurance, childcare, and other adjustments.

Other countries

🇨🇦 Canada
Federal Guidelines
🇬🇧 United Kingdom
CMS Formula
🇦🇺 Australia
8-Step Formula
🇳🇿 New Zealand
IRD Formula

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Washington Paycheck CalculatorChild Support — all statesDivorce Settlement CalculatorW-4 Withholding Assistant

How child support is calculated in Washington

Washington uses the Income Shares Model, which is the most common child support formula in the United States (used by the majority of states). The core philosophy: child support should reflect what parents would have spent on the child if the family were intact. Both parents' incomes matter because both contributed to the household before separation.

The calculation starts with combined gross monthly income. A base support obligation is looked up from Washington's schedule (based on income and number of children). Each parent then pays their proportional share. The parent with primary custody effectively pays their share directly; the non-custodial parent writes the check for their share.

1
Add both parents' gross income
Both salaries, wages, bonuses, self-employment — all income sources.
2
Look up base obligation
Washington schedule gives a total support figure based on combined income and # of children.
3
Allocate by income share
Each parent pays their % of combined income. Custodial parent keeps their share; other parent pays theirs.

Shared custody, parenting time credits, and when to modify

Custody percentage has a direct impact on child support in Washington. As the non-custodial parent's time with the child increases, their direct child-rearing costs increase — and the support obligation is adjusted downward accordingly. Most states, including Washington, apply a parenting time credit or schedule adjustment when custody approaches or exceeds a certain threshold.

Modifications to existing orders in Washington generally require a "substantial change in circumstances" — typically a 10–20% change in income, a significant change in custody time, or a major change in the child's needs. Courts don't automatically update orders; either parent must file a motion. Use this calculator to model what a new order might look like before filing.

Income change
A raise, job loss, or new income source of 10%+ typically justifies a review.
Custody change
Moving from 30% to 50% parenting time substantially changes the calculation.
New child
Additional children in either household can affect support under income shares models.
Child's needs
Significant new medical, educational, or other costs may justify an upward modification.

Frequently asked questions — Washington

Washington uses the Income Shares Model, per RCW 26.19.020. Both parents' gross monthly income is combined, a base support amount is found in the state's schedule, and each parent pays their proportional share. The non-custodial parent's share becomes the monthly payment. Adjustments are made for parenting time, health insurance, and childcare.

Both parents' gross monthly income (both matter), number of children, custody/parenting time percentage, health insurance premiums for the children, childcare costs, extraordinary medical expenses, existing child support obligations for other children, and number of other dependents.

Gross income typically includes wages, salary, commissions, bonuses, self-employment income, dividends, interest, rental income, pension/retirement distributions, and Social Security income. Courts may also impute income if a parent is voluntarily unemployed or underemployed. Enter gross monthly income — not net take-home — in the calculator.

Yes. A substantial change in circumstances — typically a 10%+ income change, change in custody, or change in the child's needs — can support a modification petition. Either parent can file with the Washington family court. Some states also have periodic review programs through the child support enforcement agency.

Courts may deviate downward for very low-income parents or unusual circumstances, but there is generally a baseline to ensure children receive some support. Guideline per RCW 26.19.020.

Washington enforces child support through wage garnishment, bank account levies, tax refund interception, passport denial/revocation, driver's license suspension, and credit bureau reporting for non-payment. The state's child support enforcement agency (IV-D program) can assist with enforcement at no cost to the custodial parent.

Child support calculators — other states

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Official sources — Washington

Washington Child Support Agency
Contact your state child support enforcement office
Office of Child Support Services (OCSS)
Federal child support resources — HHS

Washington uses income shares model. The Economic Table is updated periodically.