Washington, calculating child support depends on the custody arrangement and each parent’s income. In most cases, the parent who spends less time with the child or the non-custodial parent pays support to the other parent. The Washington State Department of Social and Health Services has developed a child support schedule worksheet calculator to help you estimate the amount of money you ought to pay. But note that there are additional ways to calculate the amount of support necessary. Even so, the judge that presides over the case still has the final say on the amount of child support you're required to pay.