Washington Child Support Calculator

Washington calculates child support from both parents’ combined monthly net income using the economic table in RCW 26.19.020, which since January 1, 2026 covers net incomes from $2,200 up to $50,000 a month. The table gives a per-child amount; the total is split by each parent’s share of net income, and health care and day care are shared in the same proportions. Washington has no automatic shared custody formula. Instead, the court may lower support when the paying parent has the children a significant amount of time. The calculator below follows the state worksheet’s standard calculation.

Gross income minus income taxes, Social Security/Medicare, mandatory pension, union dues, PFML/WA Cares premiums and maintenance paid (RCW 26.19.071(5)).
Used to identify the paying parent and flag a possible residential-time deviation.
Add-on costs (monthly, optional)
Compare your order with what the guideline produces today.

How Washington calculates child support

Washington uses an income shares model built on net income. The worksheet steps:

  1. Find each parent’s net monthly income. Start with gross income from all sources, then subtract federal and state income taxes, Social Security and Medicare, mandatory pension payments, mandatory union or professional dues, mandatory state deductions such as Paid Family and Medical Leave and WA Cares premiums, industrial insurance premiums, court-ordered maintenance actually paid, and up to $5,000 a year of voluntary retirement contributions if there is an established pattern (RCW 26.19.071(5)).
  2. Add the two net incomes and find the closest row in the economic table. The state instructions say to use the closest amount and round up at the halfway point.
  3. Multiply the per-child amount by the number of children to get the basic support obligation.
  4. Split it by income share. Each parent owes the share of the basic obligation that matches their share of combined net income.
  5. Add health care, day care and special expenses in the same proportions, then credit what each parent already pays.

Example: net incomes of $6,000 and $4,000 make $10,000 combined. For two children the table shows $1,099 per child, or $2,198. The parent earning $6,000 owes 60%, about $1,319 a month, before health care and day care.

The 2026 changes

A 2025 law (House Bill 1014, chapter 272) took effect January 1, 2026. It expanded the economic table to combined net incomes of $50,000 a month and raised the self-support reserve to 180% of the federal poverty guideline for one person. Orders entered under the old table may now produce a different number. Under RCW 26.09.170(9), once 24 months have passed since the order or its last adjustment, a change in the economic table is itself a basis to adjust support.

Limits that protect low-income parents

RCW 26.19.065 sets three limits on the paying parent’s basic obligation:

  • 45% of net income. Support for all of a parent’s children cannot exceed 45% of that parent’s net income, unless the court finds good cause, such as substantial wealth, day care costs or special needs.
  • Self-support reserve. Basic support cannot reduce the paying parent’s net income below 180% of the federal poverty guideline for one person. Using the 2026 guideline of $15,960 a year, that is about $2,394 a month.
  • Presumptive minimum. Support is at least $50 per child per month unless the paying parent shows that would be unjust.

The calculator applies all three. A court can decline to apply the limits after weighing the child’s best interests and both households’ circumstances.

Residential time and shared custody

Unlike most states, Washington has no overnight threshold that switches on a different formula. Under RCW 26.19.075(1)(d), the court may deviate from the standard calculation when the child spends a significant amount of time with the paying parent, after considering that parent’s increased costs and any decrease in the other household’s costs. The court may not deviate on that basis if it would leave the receiving household without enough to meet the child’s basic needs, or if the child receives TANF. The calculator flags cases where the paying parent has 90 or more overnights so you know this argument may be available.

Incomes above $50,000 a month

The table is presumptive up to $50,000 of combined monthly net income. Above that, the court may set support higher than the $50,000 figure, but only with written findings of fact. Below $2,200 combined, support is based on each household’s resources and living expenses, subject to the $50 per child minimum.

Changing an existing Washington order

Under RCW 26.09.170, a Washington order can be modified on a showing of a substantial change of circumstances, and the change applies only to payments due after the petition or motion. Without showing a substantial change, an order can be adjusted once 24 months have passed since it was entered or last adjusted, based on changes in either parent’s income or in the economic table. One year after entry, it can also be modified if it works a severe economic hardship or a child needs support to finish high school. Enter your current order in the calculator to compare it with the 2026 table.

The full modification process for Washington and every other state is in Navigating Child Support. Our forms app prepares the court paperwork from your answers, and the free modification audit checks whether your order is worth revisiting. Other states are in the 50-state child support calculator.

Frequently asked questions

Does Washington use gross or net income for child support?

Net income: gross income minus taxes, Social Security and Medicare, mandatory deductions and certain other items listed in RCW 26.19.071(5).

Is there a 50/50 custody formula in Washington?

No. The court may reduce support for significant residential time with the paying parent, but there is no automatic formula or overnight threshold.

What is the highest income on the Washington child support table?

Since January 1, 2026, the table runs to $50,000 of combined monthly net income. Above that, the court may order more with written findings.

What is the minimum child support in Washington?

$50 per child per month, unless the paying parent shows that amount would be unjust.

Sources

This page and calculator provide general legal information, not legal advice. Child support rules change and the court decides the final amount. For advice about your situation, consult a licensed Washington attorney.