How child support is calculated in Washington

The formula, the official tool, and the rules for low incomes and health insurance.

Checked against official sources: Oct 25, 2026.

Short answer

Washington uses the income-shares model: both parents' incomes count, and each parent pays a share of the child's support. Both parents' monthly net incomes are combined and looked up in the state economic table to find the basic support for each child.

Model
Income shares
Official calculator
Official Washington child support calculator

Get the number from Washington's official tool

Both parents' monthly net incomes are combined and looked up in the state economic table to find the basic support for each child. Each parent's share is in proportion to their income. Health care, day care and special child-rearing costs are shared in the same proportion.

Law: RCW 26.19.011-26.19.080

We don't estimate Washington's amount here: its formula uses both parents' incomes and other facts, and a home-made number could mislead you. The official tool gives the real starting number:

Official Washington child support calculator

Medical support in Washington

Parents must provide health care coverage for the child. Coverage through a parent's job or union is considered reasonable if it costs no more than 25% of that parent's basic support obligation; otherwise a parent may pay cash medical support (share of premiums, capped at 25% of basic support, plus share of uninsured costs). Health care costs are split in proportion to income.

Law: (RCW 26.09.105; WSCSS)

If the paying parent earns little in Washington

If a parent's net income is below 180% of the federal poverty guideline for one person, the presumptive minimum is $50 per child per month. Basic support cannot push the paying parent below a self-support reserve of 180% of the poverty level (except for the $50 minimum), and total support usually cannot exceed 45% of a parent's net income.

Law: RCW 26.19.065, effective Jan. 1, 2026

State guidelines may not treat time in jail or prison as choosing not to work, when support is set or changed.

Law: 45 CFR 302.56(c)(3)

The Washington guideline, step by step

Both parents' monthly net incomes are combined and looked up in the state economic table to find the basic support for each child. Each parent's share is in proportion to their income. Health care, day care and special child-rearing costs are shared in the same proportion.

Law: RCW 26.19.011-26.19.080

What the model means

Income shares means the child should get what the parents would spend if they lived together. Both incomes are combined, and each parent's share of the total sets their part.

Every state must have one set of child support guidelines, review them at least every 4 years, and use the guideline amount unless a written finding says it would be unjust.

Law: 45 CFR 302.56

In nearby states

Get your number in Washington

  1. Collect proof of income

    The formula needs each parent's income: use pay stubs and tax returns.

  2. Use the official tool

    The official number comes from Official Washington child support calculator.

  3. Include other costs

    The child's health insurance and child care costs can change the amount.

  4. Get an order

    Only a court or the agency can set the amount. Open a case with Division of Child Support (DCS), Washington State Department of Social and Health Services (1-800-442-KIDS (5437)) · Apply online

  5. Ask for free help

    Ask for free help: WashingtonLawHelp.org (legal aid network).

Where to get free help in Washington

Questions about the Washington guidelines

What formula does Washington use for child support?

Both parents' monthly net incomes are combined and looked up in the state economic table to find the basic support for each child. Each parent's share is in proportion to their income. Health care, day care and special child-rearing costs are shared in the same proportion.

Where is the Washington child support calculator?

Yes: Official Washington child support calculator.

How does Washington treat low incomes?

If a parent's net income is below 180% of the federal poverty guideline for one person, the presumptive minimum is $50 per child per month. Basic support cannot push the paying parent below a self-support reserve of 180% of the poverty level (except for the $50 minimum), and total support usually cannot exceed 45% of a parent's net income.

Is health insurance part of child support in Washington?

Parents must provide health care coverage for the child. Coverage through a parent's job or union is considered reasonable if it costs no more than 25% of that parent's basic support obligation; otherwise a parent may pay cash medical support (share of premiums, capped at 25% of basic support, plus share of uninsured costs). Health care costs are split in proportion to income.

More for Washington

Sources

Sources

Last checked: Oct 25, 2026.

Federal sources