Washington Child Support Calculator — 2026 Estimate

Washington uses the Income Shares to calculate child support. Both parents' gross monthly incomes are combined, the total child-rearing obligation is determined from the state guideline schedule, and each parent pays their proportional share. Use the calculator at childsupportestimate.com/washington-child-support-calculator/ to enter your specific income and parenting time for an instant 2026 estimate.

Yes. Washington reduces the paying parent's obligation when they have significant parenting time. Most income shares states begin applying a credit at 20-25% parenting time, increasing as time approaches 50%.

Yes. Washington child support orders can be modified when there is a substantial change in circumstances. Most states require a 10-15% change in the calculated guideline amount. Common grounds include income change, custody change, a new child, or a major change in the child's needs.

Washington includes wages, salary, overtime, self-employment income, rental income, bonuses, commissions, investment income, and Social Security or disability benefits. Courts can impute income if a parent is voluntarily unemployed below their earning capacity.

Yes. In Washington, health insurance premiums for the children and work-related childcare costs are added on top of the base child support obligation as add-ons, split proportionally between parents based on income.

File a motion to modify with the family court that issued the original order in Washington. You must demonstrate a substantial change in circumstances. Use the modification calculator at childsupportestimate.com/modification-calculator to estimate whether your change meets the threshold before filing.

Not always — but if there is disagreement about income, parenting time, or add-ons in Washington, or if you face modification, enforcement, or arrears, a family law attorney significantly improves your outcome. Most Washington family law attorneys offer free initial consultations.