How Washington calculates child support
- Each parent’s gross monthly income is reduced by income taxes, FICA, mandatory deductions, up to $5,000 a year of voluntary retirement contributions, maintenance paid and business expenses to give net income.
- The parents’ combined net income and the number of children give the basic support obligation from the economic table (presumptive up to $50,000 a month), which is shared in proportion to each parent’s net income.
- A parent’s basic obligation may not reduce their net income below the self-support reserve of 180% of the federal poverty guideline ($2,394 a month as of January 13, 2026), but is at least $50 per child per month.
- Health insurance premiums, uninsured healthcare, daycare and special expenses are shared in the same proportion, with a credit for what each parent pays directly.
- The parent the children do not mainly live with pays their standard calculation. The court may deviate, for example for a residential schedule with significant time, but not if that would leave the other household unable to meet the children’s basic needs or the children receive TANF.
What the calculator asks
- How many children is the support for?
- Who will the children live with most of the time?
- Will the children spend a significant amount of time with the parent who pays support?
- Your total gross monthly income
- Monthly federal and state income tax you pay
- Monthly Social Security and Medicare (FICA) or self-employment tax you pay
- Other mandatory monthly deductions you pay
- Voluntary retirement contributions you pay each month
- Court-ordered maintenance (spousal support) you pay each month
- Normal monthly business expenses you have if self-employed
- How many other biological or legal children do you have?
- The other parent’s total gross monthly income
- Monthly federal and state income tax the other parent pays
- Monthly Social Security and Medicare (FICA) or self-employment tax the other parent pays
- Other mandatory monthly deductions the other parent pays
- Voluntary retirement contributions the other parent pays each month
- Court-ordered maintenance (spousal support) the other parent pays each month
- Normal monthly business expenses the other parent has if self-employed
- How many other biological or legal children does the other parent have?
- Health insurance premiums you pay for the children each month
- Uninsured healthcare costs you pay for the children each month
- Daycare costs you pay each month
- Education, long-distance transportation and other special child-rearing expenses you pay each month
- Health insurance premiums the other parent pays for the children each month
- Uninsured healthcare costs the other parent pays for the children each month
- Daycare costs the other parent pays each month
- Education, long-distance transportation and other special child-rearing expenses the other parent pays each month
It never asks for names, Social Security numbers or account numbers, and your answers are not saved.
What the estimate leaves out
- Equal residential time and children living with each parent (residential split adjustment)
- Deviations from the standard calculation (RCW 26.19.075), including the residential-schedule deviation
- Imputed income: enter any imputed amount as income
- More than five children, and support above the economic table for combined net income over $50,000
- Post-secondary educational support and the additional factors listed in worksheet Part VIII
When a situation is outside what the calculator covers, it says so and points you to the official worksheet instead of guessing.
Official sources
- RCW 26.19.020, economic table (eff. January 1, 2026)
- RCW 26.19.065, limits, self-support reserve and $50 minimum
- RCW 26.19.071, standards for determination of income
- RCW 26.19.075, standards for deviation (including the residential schedule)
- Washington State Child Support Schedule: definitions, standards, instructions and economic table (06/2026)
- Washington State Self-Support Reserve ($2,394 as of January 13, 2026)
Washington State Child Support Schedule Worksheets (WSCSS-Worksheets 06/2026) →
Ready to estimate? The calculator shows each worksheet line so you can check it against the official form.
Open the Washington calculator →An estimate from the published guideline formula, not a prediction of a court order. The official court worksheet and the court’s decision control. General information, not legal advice. LawCat is not a law firm.