How Child Support Is Calculated
Child support isn't negotiated from scratch. Every state has child support guidelines, a formula the court must apply, and judges can only depart from it for reasons the law allows. Knowing how the formula works tells you most of what your order will look like.
The main formula types
- Income shares. Used by most states. The formula estimates what the parents would have spent on the child if they lived together, based on their combined income, then splits that amount in proportion to each parent's income.
- Percentage of income. A smaller group of states sets support as a percentage of the paying parent's income, rising with the number of children.
- Melson formula. A few states first set aside a basic self-support amount for each parent, then apply percentages to what's left.
Your state's child support agency or court website usually has an official calculator for its formula.
What goes into the number
- Income of both parents: wages, self-employment profit, bonuses, commissions and often other sources. If a parent is voluntarily unemployed or underemployed, a court can impute income based on what they could earn.
- Parenting time. Many states reduce support when the paying parent has the children a significant share of overnights.
- Number of children.
- Add-ons: health insurance premiums, uninsured medical costs and work-related childcare are often split separately.
- Other children a parent supports may lead to an adjustment.
When can a court go above or below the guideline?
Judges can "deviate" when applying the formula would be unjust or inappropriate, for example for a child's special needs or unusually high or low incomes. They usually have to explain why in writing.
How long it lasts
Generally until the child turns 18 or finishes high school, though some states extend support for college or for an adult child with a disability. Support is the child's right, so parents usually can't simply agree to waive it.
Changing an order
You can ask the court to modify support after a substantial change, such as a significant change in either parent's income, a change in custody, or new needs. Until the court changes the order, the old amount stays due, so file as soon as your situation changes. Missed payments build up as arrears that generally can't be erased, and states can collect them through wage garnishment, tax refund interception and license suspension.
A family law attorney can check the numbers going into the formula, which is where most disputes are. Related: how child custody is decided.
This guide is general information, not legal advice. Child support formulas differ by state.