Seattle Child Support: Calculation, Filing, and Modification

Seattle child support is handled by King County Superior Court using Washington’s statewide formula: the court combines both parents’ net monthly incomes, looks up a basic support amount on the state’s economic table based on the number of children, and splits that amount between the parents in proportion to what each one earns.¹² The parent with less residential time generally writes the check. Because support legally belongs to the child, parents cannot agree between themselves to skip it.

How the Support Amount Is Calculated

The starting point is each parent’s net monthly income. Added together, that combined figure runs through the Child Support Economic Table under RCW 26.19.020, which produces a basic obligation keyed to the number of children.³ The table steps up when a child turns twelve.²

Each parent then owes a share proportional to their contribution to the combined income. Earn 60% of the total, owe 60% of the support. The table is presumptive up to a combined net monthly income of $50,000; above that, a judge can order more but must put the reasoning in written findings.³

What Counts as Income

Support is calculated on net monthly income, not gross pay. RCW 26.19.071 defines gross income broadly to include wages, commissions, bonuses, unemployment benefits, deferred compensation, and self-employment earnings.⁴ From that number you subtract only a specific set of deductions to get to net:

Federal and state income taxes
FICA (Social Security and Medicare withholding)
Mandatory pension payments
Mandatory union or professional dues
State industrial insurance premiums
Court-ordered spousal maintenance you actually pay
Voluntary pension contributions up to $5,000 per year, with documentation
Normal business expenses and self-employment taxes for self-employed parents, limited to expenses that reduce personal income

Credit card bills, car loans, and other personal debts are not deductible for this calculation.⁴

When the Standard Amount Can Be Adjusted

Judges can deviate from the table figure when specific circumstances justify it. RCW 26.19.075 lists the allowed reasons, and the ones that come up most often in King County cases include:⁵

A residential schedule where the paying parent has substantial time with the child, though the court cannot reduce support if doing so would leave the receiving household unable to meet the child’s basic needs.
Special needs of the children, including disabilities, extraordinary medical costs, or unique educational or psychological requirements.
Extraordinary debt that the parent did not voluntarily incur.
Nonrecurring income like overtime, bonuses, or contract work; the court looks at the prior two calendar years to decide what to count.
Significant wealth and assets, including savings, investments, real estate, and pensions.
Support actually being paid for children from other relationships.

A new spouse or partner’s income cannot by itself justify a deviation; it only matters if the parent is also requesting a deviation on one of the listed grounds.⁵

Deviations also work in the other direction. If a parent is voluntarily unemployed or underemployed, the court is required to impute income based on work history, skills, education, health, age, criminal record, and the local job market.⁴ A parent who already works full time cannot have income imputed unless the court finds the underemployment is specifically meant to lower child support.

Health Insurance Is Part of Every Order

Every Washington child support order must include a medical support obligation. Under RCW 26.09.105, both parents are required to provide health care coverage, and the court allocates the cost.⁶

A parent must provide accessible insurance when the cost does not exceed 25% of that parent’s basic support obligation. Free employer or union coverage must be used regardless. When neither parent has affordable employer coverage, the court can order contributions toward public health care premiums, and it can require coverage above the 25% threshold if that serves the child’s best interests. Once ordered to enroll a child, a parent has 20 days to show proof.⁶

How to File in King County

To open a case, file a petition with your completed Washington State Child Support Schedule Worksheets at King County Superior Court.⁷ The court operates at the King County Courthouse in downtown Seattle and at the Maleng Regional Justice Center in Kent. A dissolution of marriage costs $364 to file; a parentage action costs $310, and a fee waiver is available if you cannot afford either.⁸

You will also complete a Financial Declaration listing income, expenses, assets, and debts, and attach supporting records like tax returns and pay stubs. Self-employed parents should bring profit and loss statements and business filings so the court does not impute a higher figure based on thin records.⁹

After filing, you must serve the other parent under Superior Court Civil Rule 4. A neutral adult who is not a party to the case delivers the papers, and the other parent has 20 days to respond if served inside Washington. Missing that window can produce a default order built entirely on your numbers.¹⁰

If both parents agree on the number, you can submit a signed order for a family law commissioner to sign off without a hearing. If you cannot agree, the commissioner holds a hearing and enters the order. You can also skip court entirely and work through the Washington State Division of Child Support, which runs an administrative process that establishes and enforces orders outside the court system.¹¹

Getting Support Fast With a Temporary Order

Final orders can take months. Either parent can file a motion for a temporary family law order that puts child support in place while the case is pending. The motion requires the same worksheets and financial declaration as a final order, plus a notice of hearing served on the other parent.¹² A temporary order carries the same legal weight as a final order, and the same enforcement tools apply if payments are missed.

Changing an Order Later

Either parent can petition to modify support by showing a substantial change in circumstances, such as a significant income change or newly developed medical or educational needs for the child.¹³ Voluntarily quitting a job or cutting hours does not count on its own.

Some modifications are available without proving a substantial change:

After 24 months, based on income changes or updates to the economic table.
After one year, if the current order causes severe economic hardship to a parent or the child, or to extend support for a child still finishing high school after turning 18.
When the paying parent is incarcerated for at least six months, a prospective modification is available.

If DCS is on the case, it can file for modification when the current order is at least 15% above or below what the standard calculation would produce.¹³ Any modification only applies to payments coming due after the petition is filed, so do not wait once circumstances have shifted.

What Happens If Payments Stop

Washington’s collection tools are aggressive, and DCS can use most of them without going back to court. Under Chapter 74.20A RCW, the agency can place liens on property, issue orders to withhold money from bank accounts, intercept state and federal payments including tax refunds and unemployment benefits, and seize and sell property through distraint.¹⁴

License suspension reaches further than most people expect. DCS can suspend a Washington driver’s license for nonpayment, along with hunting, fishing, business, professional, and contractor licenses.¹⁵ Federal consequences stack on top: owe more than $2,500 in past-due support and the U.S. State Department can deny or revoke your passport.¹⁶

Unpaid support in the state registry also accrues interest at 12% per year.¹⁷ A $10,000 arrearage grows by $1,200 every year it sits unpaid.

When Child Support Ends

Support generally runs until a child turns 18. If the child is still enrolled in high school at that point, the court can extend support through graduation, and a modification for this purpose does not require a substantial change in circumstances.¹³

Washington courts can also order post-secondary educational support, though for college the economic table is advisory rather than binding. The court weighs the child’s age, academic abilities, career goals, the expectations the parents had together, and the parents’ resources. The child must attend an accredited school, actively pursue coursework tied to their goals, keep good academic standing, and share grades with both parents.¹⁸

Post-secondary support cannot continue past the child’s 23rd birthday absent exceptional circumstances such as a disability. A child who drops out or loses good standing has support automatically suspended until they return to school in good standing.¹⁸

Taxes

One boundary worth knowing: child support is tax-neutral at the federal level. The payer cannot deduct it, and the recipient does not report it as income.¹⁹ Which parent claims the child as a dependent is a separate question handled through IRS Form 8332, not through the support order itself.

1
King County. Superior Court Jurisdiction – King County, Washington
2
Washington State Legislature. Washington Code 26.19.011 – Definitions
3
Washington State Legislature. Washington Code 26.19.020 – Child Support Economic Table
4
Washington State Legislature. Washington Code 26.19.071 – Standards for Determination of Income
5
Washington State Legislature. Washington Code 26.19.075 – Standards for Deviation from the Standard Calculation
6
Washington State Legislature. Washington Code 26.09.105 – Mandatory Medical Support
7
Washington State Courts. WSCSS Schedule and Worksheets
8
King County. Superior Court Clerk’s Office Fee and Payment Information
9
Washington State Courts. Financial Declaration
10
Washington State Courts. Superior Court Civil Rules – CR 4 Process
11
Washington State Department of Social and Health Services. Administrative Order
12
Washington State Courts. Court Forms – Temporary Family Law Order – Child Support (Divorce)
13
Washington State Legislature. Washington Code 26.09.170 – Modification of Decree for Maintenance or Support
14
Washington State Legislature. Chapter 74.20A RCW – Support Enforcement
15
Washington State Legislature. Washington Code 74.20A.320 – License Suspension
16
U.S. Department of State. Passports and Child Support Debt
17
Washington State Legislature. Washington Code 26.23.030
18
Washington State Legislature. Washington Code 26.19.090 – Post-Secondary Educational Support
19
Internal Revenue Service. Publication 504, Divorced or Separated Individuals