How to Calculate Child Support Payments in Washington State

Learn how to calculate child support in Washington State, when the amount of support may be different than the standard calculation, and how to apply for, collect, and modify child support.

By , Legal Editor

Washington's child support guidelines set out the rules for calculating each parent's support obligation. Typically, the noncustodial parent (the one who has the children less than half the time) will pay their share to the custodial parent. The state then assumes that the custodial parent spends their share directly on the child's daily expenses, like housing, food, and clothing.

How to Use Washington's Child Support Calculator

You can get a rough estimate of your monthly child support obligation with Washington's Quick Child Support Estimator. But for a more accurate calculation, you should use the state's automated child support worksheet. This is the same worksheet that you'll submit to the court as part of your divorce or other child support proceeding.

You'll need to have some basic information on hand before doing the calculations, including both parents' tax returns for the past two years, a list of your assets and debts, and certain child-related expenses (including health insurance premiums, unreimbursed health care, day care, education, and long-distance transportation for parenting time). You can find details on what's included in gross and net income at Wash. Rev. Code § 26.19.071 and in the instructions with the Washington State Child Support Schedule.

Are Other Child Support Calculators Accurate?

Watch out for other websites with so-called child support calculators for Washington State. Unfortunately, there's no guarantee that these calculators are accurate and up-to-date. The state updates its child support guidelines regularly, and you usually can't tell whether any of these other websites have kept up with the latest changes.

It's best to stick with the official state calculator to get the most accurate estimate of the amount of child support you may pay or receive. Be aware, however, that the judge may order a different amount in your case.

When Child Support May Be Different Than the Guideline Calculation

Washington presumes that the standard calculation will result in an appropriate amount of child support. But you may argue that a different amount would be better in your situation. Whether you and the child's other parent have agreed on a support amount that departs from the guideline or a judge decides for you, the judge will have to find that it would be unfair to use the standard calculation. The guidelines list some of the reasons that may justify a deviation from the standard calculation. (Wash. Rev. Code § 26.19.075 (2024); In re Marriage of Selley, 359 P.3d 891 (Wash. Ct. App. 2015).)

How to Apply for Child Support in Washington State

Typically, you'll apply for child support as part of the process of filing for divorce in Washington. If you aren't married to your child's other parent, you may get help with requesting support by enrolling for child support services with the Division of Child Support (DCS) in the Washington State Department of Social and Health Services. If needed, the DCS may also help establish the child's parentage.

How to Collect Child Support in Washington

Typically, parents pay child support by having the payments withheld from their wages and then forwarded to the other parent. But when wage withholding isn't appropriate (such as when a noncustodial parent is self-employed or between jobs), the state offers other ways to pay support.

Washington's DCS can help if you're having trouble collecting support payments. Depending on how much the other parent owes, the agency has several ways of enforcing child support, including withholding support from paychecks, reporting the debt to credit bureaus, intercepting income tax refunds, intercepting workers' compensation or unemployment benefits, seizing assets, and getting the parent's driver's or other licenses suspended.

How to Change the Amount of Child Support

Either parent may request a change in an existing child support order. The rules for modifications are different depending on how long it's been since the existing order was issued or last reviewed:

  • If it has been at least two years, the support amount may be adjusted based on changes in either parent's income or in the state's economic table and guidelines.
  • If it's been at least one year, the judge may grant a modification if the existing child support order is causing severe economic hardship on either parent or the child, if the child has turned 18 but still needs support while completing high school, or if the existing order requires periodic adjustments.
  • At any other time, a parent who's requesting a modification will need to show that there's been a substantial change in circumstances since the existing order was issued.

If you have an open case with the Washington DCS, you may ask the agency to review your child support order to see whether a modification is warranted. If the review shows that the support amount is at least 15% different than the guideline calculation under your current circumstances, the agency may initiate the modification action for you.

(Wash. Rev. Code §§ 26.09.170, 26.09.175 (2024).)

Without agency help, you'll need to file a petition or motion with the court, along with updated child support worksheets. Unless the child's other parent has agreed to a modified amount, you should strongly consider speaking with a family law attorney who can guide you through the legal process and argue your case in the court.

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