Washington uses an income shares model built on net income. Each parent’s gross income is reduced by taxes, FICA, mandatory pension and union dues, mandatory state premiums for paid family leave and WA Cares, maintenance actually paid and up to $5,000 a year of regular voluntary retirement contributions. The two net figures are added together, a basic support obligation per child is read from the economic table in RCW 26.19.020, and that obligation is divided between the parents in proportion to what each of them earns.
Three things then adjust it. The children’s health insurance, work-related day care and special expenses are added and shared in the same proportions, with credit to whoever actually pays them. The paying parent’s basic obligation is then tested against two limits: it may not exceed 45 percent of that parent’s net income, and it may not push that parent below the self-support reserve. Finally, the court may deviate from the standard calculation, most often for the residential schedule, but only with written findings.
