How Child Support Is Calculated in Washington

Washington uses an income shares model, the Washington State Child Support Schedule. The basic support obligation comes from an economic table based on the parents' combined monthly net income and number of children, and is divided according to each parent's share of combined net income. Health care, day care and special expenses are shared in the same proportion. A self-support reserve of 180% of the federal poverty level applies. Worksheets must be filed in every child support case; DSHS's Division of Child Support provides an online worksheet calculator for estimates.

Parents who do not have an open case with the DSHS Division of Child Support (DCS) can enroll by requesting the forms through the online application form or printing them (Forms 18-078 and 14-057, plus 18-433 if a support order already exists), calling 800-442-KIDS (5437), or picking them up at a DCS office. Forms can be emailed, mailed to DCS Central Services (P.O. Box 11520, Tacoma, WA 98411), faxed or hand-delivered. One enrollment form is needed for each noncustodial parent. Families receiving TANF do not need to apply; a case opens automatically. DCS says it sends a letter with a case number within 7 to 10 days.

Unless the parents agreed otherwise in writing or the decree says otherwise, child support ends when the child is emancipated. An order may be modified to extend support past age 18 for a child who is still in high school. Separately, a court may order support for postsecondary education for a child who is still dependent on the parents and who attends an accredited school, pursues a course of study and stays in good academic standing; this support cannot be ordered past the child's 23rd birthday except in exceptional circumstances, such as a mental, physical or emotional disability.

A support order can generally be modified only for installments due after the motion is filed and only on a showing of a substantial change of circumstances. One year or more after the order is entered, it may be modified without a substantial change in some situations, such as severe economic hardship or to extend support for a child still in high school. If 24 months have passed since the order or its last adjustment, it may be adjusted based on changes in the parents' incomes or in the economic table, without a substantial change. Parents with an open DCS case can ask DCS to review their order at any time; if the order is a court order, the request goes through the county prosecutor's office.

Washington law lets DCS collect unpaid support through liens on property, orders to withhold and deliver income or assets, actions against bank accounts (including financial institution data matches), seizure and sale of property under a lien, collection from industrial insurance disability payments and from state income tax refunds. If a parent is about six months (180 days) or more behind, DCS can certify the parent to have driver's, professional and other state licenses, and fish and wildlife licenses, suspended or not renewed. The parent can avoid certification within 20 days of notice by paying in full, asking for a hearing, agreeing to a payment schedule, or filing to modify the order.

Washington's child support agency is the Division of Child Support (DCS) of the Department of Social and Health Services (DSHS). DCS enforces child support, establishes parentage, modifies support orders and offers alternative solutions, and works with employers on new hire reporting and income withholding. People without an open case can enroll in child support services or use the Child Support Application. Support can be paid through income withholding or the DCS online payment portal. Contact: 800-442-KIDS (5437).

The Washington State Child Support Schedule (WSCSS) Worksheet Calculator, run by DSHS's Division of Child Support, helps parties estimate the amount of child support that might be ordered in their own cases. Amounts calculated are advisory only; the superior court judge, court commissioner or administrative law judge has the final authority to set support. The calculator does not save your entries. The page notes that child support schedule laws were amended by Engrossed House Bill 1014, with changes effective January 1, 2026.