Child Support Calculator

About 40 states use the Income Shares model, which combines both parents' incomes and assigns a share based on each parent's percentage of the total. Other states use the Percentage of Income model (a percentage of the noncustodial parent's income) or the Melson formula. Adjustments are made for health insurance, childcare, and parenting-time overnights.

Courts generally must follow the state guideline amount but can deviate for documented reasons such as extraordinary medical needs, private school tuition, very high or very low income, or shared custody arrangements with substantial overnights for both parents.

Most states allow modification when there has been a substantial change in circumstances - commonly a 15-20% income change, job loss, a new child, or a significant change in custody. Some states also allow review every 3 years regardless of changes. Modifications are not retroactive before the filing date.

Enforcement tools include wage garnishment, tax-refund interception, license suspension (driver, professional, recreational), passport denial, liens, and contempt of court that can include jail time. Federal law also enables interstate enforcement under UIFSA.

In most states, child support ends when the child turns 18 or graduates from high school, whichever is later. A few states extend it to 19, and some (such as New York and Mississippi) run to 21. Support can continue indefinitely for a disabled child, and some states allow support for college costs.

Usually yes. Even with equal parenting time, the higher earner typically still pays support, because guidelines aim to keep the child's standard of living similar in both homes. The 50/50 split reduces the amount but rarely eliminates it when incomes differ.

Often not within the base amount. Most states add health-insurance premiums, uninsured medical costs, and work-related childcare on top of the guideline figure, split between the parents in proportion to their incomes.