A set of legal rules and formulas used to calculate how much financial support a parent should pay for a child, usually based on each parent's income, the child's needs, and the parenting arrangement.

In practice, these guidelines give courts and parents a starting point that is meant to be consistent rather than arbitrary. They often account for wages, self-employment income, certain benefits, childcare costs, health insurance, and the number of overnights each parent has. A judge can sometimes depart from the guideline amount, but usually only when there is a recognized reason and supporting evidence. In Hawaii, child support is generally calculated under the Hawaii Child Support Guidelines, adopted by the Hawaii Family Court under Hawaii Revised Statutes chapter 576D. The formula is updated periodically, and courts use worksheets to apply it.

These guidelines matter because the support amount can affect a divorce, custody case, or later modification request. If a parent is injured and cannot work, that drop in income may justify asking the court to change support, but the order does not change automatically. Past-due support can still accumulate as arrears. If an injury claim or settlement includes lost wages, that money may also be reviewed when support is recalculated or enforced through wage garnishment or other collection methods.