Washington Child Support Calculator

How Washington Calculates Child Support

Washington determines child support using the Income Shares Model, the standard set out in RCW 26.19. Under this model, the incomes of both parents are combined to estimate what they would have spent on the children if the family were intact, and that total obligation is then divided between them in proportion to each parent's share of the combined income.

The calculator above applies that formula to the income and expense figures you enter and shows each step of the math, so you can see exactly how the estimate is built. Because every order ultimately runs through a judge, the guideline figure is a starting point rather than a guaranteed result — the sections below explain what goes into it and where real orders can differ.

Key Rules Behind the Washington Formula

• Washington determines child support using the "Economic Table" (RCW 26.19.020), which is the state's version of the Income Shares model and lists basic support obligations by combined net monthly income and number of children. The current table is effective January 1, 2026.
• Unlike most Income Shares states, Washington does NOT automatically apply a parenting time credit based on overnights. Under RCW 26.19.075(1)(d), a residential credit may be applied when the non-custodial parent exercises substantial residential time, but it requires a specific court finding — it is not triggered by hitting a fixed overnight count threshold.
• The Economic Table covers combined net monthly income from approximately $1,000 to $12,000 per month. For incomes above the table maximum, the court exercises discretion to set an appropriate support amount.
• Health insurance premiums for the children, day care costs, and long-distance transportation costs for visitation are added to the basic obligation and divided proportionally between parents based on each parent's share of combined income.
• Washington courts may deviate from the standard calculation when the child has special needs, when a parent has significant debt from a prior relationship, or when application of the guidelines would be unjust based on the totality of the circumstances.

What Counts as Income

Child support guidelines are built on each parent's income, so the figure you enter matters more than any other input. Most states start from a broad definition of gross income that includes wages, salary, tips, commissions, bonuses, self-employment earnings, and many forms of government benefits, then subtract specific deductions to reach the income the formula actually uses.

Washington's rules under RCW 26.19 spell out which deductions apply and whether the formula runs on gross or net income. The calculator's field labels tell you which figure to enter; when in doubt, use your most recent pay stubs and tax return, and confirm the details in the Washington child support laws guide.

How to Establish a Child Support Order in Washington

A child support obligation becomes enforceable only once a court or the state child support agency issues an order. Either parent can request one, and in Washington, as in every state, the local child support agency that operates under the federal Title IV-D program can open a case, locate the other parent, establish paternity if needed, and ask the court to set support using the guideline formula.

When you apply, expect to provide proof of income for both parents, the child's information, and details about health insurance and childcare costs — the same inputs this calculator uses. Running your numbers here first gives you a realistic idea of the order amount before you file.

How to Modify a Washington Child Support Order

Child support orders are not permanent. Washington courts can revisit an order when there has been a substantial change in circumstances — for example, a significant change in either parent's income, a change in custody or parenting time, or a meaningful change in the child's needs. Federal rules also entitle parents in IV-D cases to request a review periodically (often about every three years) even without a major change.

To estimate a new amount, re-run the calculator with the updated figures. If the guideline result is meaningfully different from your current order, that gap is often what supports a modification request — though only a court can actually change the order.

How Child Support Is Enforced in Washington

Once an order is in place, Washington has strong tools to collect it. The most common is income withholding: federal law requires most new orders to be paid through automatic wage garnishment, so payments are deducted from the paying parent's paycheck. When payments fall behind, enforcement can escalate to intercepting tax refunds, suspending driver's or professional licenses, placing liens on property, reporting the debt to credit bureaus, and, in serious cases, contempt-of-court proceedings.

Interest and penalties can accrue on unpaid support, so an order that goes unaddressed tends to grow rather than disappear. If your circumstances have changed, seeking a modification through the court is almost always better than simply paying less than the order requires.

Disclaimer

This calculator provides estimates only and is not a substitute for legal advice. The actual amount ordered by a Washington court may differ based on factors including but not limited to: the special needs of the child, travel expenses for visitation, extraordinary educational or medical expenses, the parents' other support obligations, and the court's discretion to deviate from the guidelines. For advice about your specific situation, consult a licensed Washington family law attorney.

← Read the full Washington child support laws guide