Most states have child support guidelines in their statutes—often in the statutes collected in the state’s family code. These child support guidelines provide percentages and methods of calculating child support payments based on the number of children; the parents’ incomes and financial resources; the income and needs of the custodial parent; the needs of the children, including any special needs; and the standard of living for the children before the parents’ divorce or separation. The child support guidelines are just guidelines, and the court generally has discretion to order more or less child support based on the best interest of the children.

In Washington State, child support guidelines are established by state law to ensure that children receive the financial support necessary for their well-being. These guidelines are found in the Revised Code of Washington (RCW) 26.19. The state uses a model that considers the income of both parents, the number of children, and the children's living arrangements to determine the amount of child support. The guidelines provide a standard calculation that takes into account each parent's income, the children's health care and education expenses, day care costs, and other factors. While these guidelines serve as a baseline for determining child support, Washington courts have the discretion to deviate from the guidelines when it is in the best interest of the child. Factors that may lead to a deviation include the special needs of the child, the child's age, the parents' financial resources, the standard of living the children would have enjoyed had the household remained intact, and other considerations relevant to the children's best interests.