Calculating Child Support in Washington State

In cases involving children, courts will enter an order providing for the financial support of the child. Typically, the non-custodial parent (that is, the parent spending less time with the child) will be the parent who will be court-ordered to pay child support to the custodial parent. Washington law requires that the court take many factors into account.

First, the court will consider the gross incomes of both the mother and father. Gross income is income from any source. This means not only your normal wage from your “day job,” but income from other sources, such as a second job, income from a rental properly, or alimony received. The court will then take allowed deductions from that gross monthly income to determine both parties’ net income. These deductions include such things as income tax, union dues, business expenses, or alimony that is paid. The net income of both parents is then added together to determine the net resources available to support the child.

Based on this combined number, the court will then look at the basic monthly support obligation for the child. This table can be found on the Washington State Legislature website. The court will then divide the support obligation based on the percentage of the net income contributed by each parent. For example, if the non-custodial parent makes 75% of the combined net income of the parents, then the non-custodial parent will be responsible for paying 75% of the amount indicated by the support obligation table. This provides the basic support obligation.

After determining the basic support obligation, other factors must be considered. For example, the calculation will take into account daycare costs paid for the child. Health insurance premiums are also factored in. If the child has extraordinary health care costs or other special needs, this may also play a part in the ultimate calculation.

Should the ultimate child support amount seem unfair, there are ways to ask the court to deviate from the typical child support guidelines. A parent can ask the court to consider other factors such as child support received for the support of children from other relationships, recurring gifts, cost of living differences of the parents, or other sources of wealth not already taken into account by the typical child support calculation. Based on these or other factors, a court commissioner or judge could deviate from the child support calculation.

Clearly child support calculations can be quite technical, and it is best to discuss these issues with your attorney. If you are facing a child support case–whether as the custodial or non-custodial parent–call our office at (253) 272-9459 to discuss your options. You can also email us at


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