Washington child support calculator

Washington follows the income-shares model. The idea is that a child should receive the same proportion of parental income they would have if the parents lived together. Both parents’ net monthly income is combined, the per-child basic support amount is read from the economic table and multiplied by the number of children, and each parent is responsible for the share that matches their percentage of the combined net income. The parent the children do not primarily live with pays their share to the other.

The heart of the calculation is the economic table in RCW 26.19.020 — it gives the basic support obligation per child, indexed by combined net monthly income (from $2,200 up to $50,000) and the number of children (one to five). You read the per-child amount for your income and number of children, then multiply by the number of children. This calculator uses the current table, adopted by 2025 c 272.

To the basic obligation Washington adds work-related day care and the children’s health-care premium, which are shared in proportion to income (RCW 26.19.080). Washington also sets limits: a presumptive minimum of $50 per child per month, a self-support reserve, and a presumptive ceiling so a parent’s support does not exceed 45% of net income absent good cause (RCW 26.19.065).

When the children spend substantial time with the paying parent, the court may grant a residential-schedule credit (RCW 26.19.075), but it is discretionary — not automatic — and it may not leave either household below its need standard. Because it depends on the specific residential schedule and the court’s findings, this calculator computes the standard basic obligation before any such deviation.

It combines both parents’ net income, reads the RCW 26.19.020 economic table, multiplies by the number of children, adds day care and health-care premiums, and splits the total by income share. It does not compute net income from your pay stubs, apply a residential-schedule credit, run the self-support-reserve test in detail, add extraordinary expenses, or apply a deviation the court may order. For a figure you can file, use the Washington child support worksheets or consult an attorney.