How is Child Support Calculated in Washington State?

Washington calculates child support using an economic table that matches both parents' combined net incomes to a schedule of basic support obligations. The 2026 update to the schedule dramatically expanded its coverage — the table now goes up to $50,000 combined monthly net income, up from the old $12,000 cap. For many families who previously fell above the cap and relied on judicial discretion, this update brings clear guideline amounts for the first time.

Washington uses net income — income after taxes and mandatory deductions — which is an important distinction from states like Virginia that use gross income.

Step One: Calculate Net Monthly Income for Each Parent

Washington's child support schedule under RCW 26.19.020 begins with each parent's net monthly income — what remains after federal and state income taxes, FICA (Social Security and Medicare), mandatory pension contributions required by the employer, union dues, and prior child support orders.

All sources of income count toward gross income before those deductions: wages, salary, self-employment income, bonuses, commissions, overtime, rental income, investment income, unemployment benefits, disability payments, and retirement or pension income. Courts may also impute income — assume a parent could earn more — if they are voluntarily underemployed or unemployed without good cause.

Step Two: The 2026 Economic Table Update

The 2026 Washington child support schedule took effect January 1, 2026 and fundamentally changed how higher-income families are handled. The economic table previously covered combined monthly net incomes up to $12,000 — a cap that left a large number of Washington families above the guideline and dependent on judicial discretion for their numbers. The 2026 schedule extends the table to $50,000 combined monthly net income, giving most families a clear guideline starting point.

The lower end of the table also shifted — the schedule now starts at $2,200 combined monthly net income, up from a lower floor in the prior schedule. This reflects Washington's self-support reserve — a minimum income threshold below which child support may be reduced to prevent the paying parent from falling below subsistence level.

Approximate figures based on the 2026 Washington Child Support Schedule (RCW 26.19.020, effective January 1, 2026). Actual amounts depend on the precise income level and schedule in effect at the time of the order.

Step Three: Divide the Obligation Proportionally

Once the basic obligation is found in the table, it's divided between parents based on each parent's share of combined net income. If Parent A earns 60% of combined net income, Parent A is responsible for 60% of the basic obligation. Parent B is responsible for 40%.

In a sole residential arrangement — where one parent is the primary residential parent — the other parent's share flows to the primary parent as a direct monthly payment. The primary parent's share is presumed spent directly on the child during their time together.

Parenting Plan Adjustments

Washington uses the residential schedule established in the parenting plan to adjust child support. The more time a parent spends with the children, the more direct child-related costs they bear — and the guidelines account for that.

Washington applies adjustments based on the number of overnights the non-primary-residential parent has per year. Parents with fewer than 90 overnights per year are generally treated under the standard calculation. Parents with 90 or more overnights per year — roughly every other weekend plus additional time — receive a credit that reduces the support transfer. In shared residential arrangements where each parent has the children close to half the time, the adjustment can substantially reduce or even zero out the transfer payment if both parents have similar incomes.

Courts have discretion to deviate from the standard calculation based on the specific residential schedule and each parent's actual child-related expenses. The parenting plan and the child support order are developed together in Washington cases, making the residential schedule and the support calculation closely linked.

Add-Ons: Health Care and Childcare

Health care costs and work-related childcare expenses are not in the economic table — they're shared proportionally on top. Under RCW 26.19.080, each parent pays their proportional share of the child's monthly health insurance premium (the portion attributable to the child) and work-related childcare costs. The proportions are the same income-share percentages used for the basic obligation.

Ordinary medical expenses — routine co-pays and prescriptions — are typically included in the base support obligation and not added separately. Extraordinary medical expenses above a defined threshold may be shared proportionally. Courts may also address recurring special expenses such as tutoring, therapy, or extracurricular activities on a case-by-case basis.

Above the $50,000 Cap

When combined monthly net income exceeds $50,000, the economic table no longer provides a direct number. Courts start with the obligation at $50,000 and may exceed it based on written findings that consider the child's needs, the parents' lifestyle during the marriage, and each parent's ability to pay. Above the cap, child support becomes more discretionary — judges look at what the child actually needs rather than applying a formula.

When Does Child Support End in Washington?

Washington child support generally ends when a child turns 18, or graduates from high school — whichever is later — but not past age 19. A child who turns 18 mid-school-year continues receiving support until graduation, up to the age 19 cap.

If the child has a developmental disability that prevents self-sufficiency, courts may order support to continue past 19. Washington does not generally require parents to contribute to college costs through a child support order — unlike New Jersey, which has a mechanism for college contribution. College expenses, if agreed upon, are typically handled through the separation agreement rather than the guidelines.