How is child support calculated in Washington?

Monthly net income

Gross income includes income from any source, such as wages, overtime, bonuses, self-employment income, and Social Security and disability benefits, apart from listed exclusions like a new spouse’s income, gifts, TANF, and SSI (RCW 26.19.071(3) and (4)). Taxes, FICA, mandatory pension payments and union dues, court-ordered maintenance actually paid, and other listed items are deducted to reach net income (RCW 26.19.071(5)).

The court must impute income to a parent who is voluntarily unemployed or underemployed, but not to a parent who is unemployable, and not to a parent employed full time unless it finds the parent is purposely underemployed to reduce support (RCW 26.19.071(6)).

The economic table

The table that took effect January 1, 2026 is presumptive for combined monthly net incomes up to and including $50,000. Above that, the court may exceed the presumptive amount for $50,000 on written findings (RCW 26.19.020 and 26.19.065(3)). For combined incomes below $2,200, the table says the obligation is based on the resources and living expenses of each household.

Added expenses and limits

Health care costs, day care, and special child rearing expenses such as tuition and long-distance transportation for visits are shared in the same proportion as the basic obligation (RCW 26.19.080(2) and (3)).

A parent’s support obligation for all of that parent’s children may not exceed 45 percent of net income except for good cause shown. When a parent’s net income is below 180 percent of the federal poverty guideline for one person, a minimum order of $50 per child per month is presumed unless the parent shows that would be unjust (RCW 26.19.065).

Deviations and residential time

The court may deviate from the standard calculation for reasons listed in RCW 26.19.075, such as possession of wealth, extraordinary debt not voluntarily incurred, or children from other relationships, and must explain any deviation in written findings. Agreement of the parties alone is not enough (RCW 26.19.075(5)).

There is no automatic overnight threshold. The court may deviate if the child spends a significant amount of time with the paying parent, but not if that would leave the receiving household without enough to meet the child’s basic needs or if the child receives TANF (RCW 26.19.075(1)(d)).