Child Support Calculator — Federal Income Shares Estimate
Estimate monthly child support using the federal Income Shares baseline, with adjustments for shared custody, health insurance, and childcare. State-specific results require a family law attorney or state child support agency.
Each state uses its own formula. This tool gives a federal-baseline estimate, not a state-court calculation.
Nights per year the child spends with Parent A. 50/50 = 183.
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Frequently asked questions
How is child support calculated?
Roughly 38 states use the Income Shares model: combine both parents' incomes, apply a guideline percentage based on number of children (federal baseline: 17% for 1 child, 25% for 2, 29% for 3, 31% for 4, 35% for 5+), then split the obligation in proportion to each parent's income share. The non-custodial parent pays their share to the custodial parent. Other states use Percentage of Obligor Income or the Melson Formula, which yield different numbers.
Does custody time affect the amount?
Yes, in most states. When the non-custodial parent has the children for more than about 30% of overnights (110+ nights per year), a 'cross-credit' or 'shared parenting adjustment' reduces their payment. The exact formula varies: some states use a linear sliding scale, others a step-function. Near-50/50 custody can reduce the payment to a small income-equalization amount or zero.
What income counts?
Gross income from all sources usually counts: wages, salary, commissions, bonuses, self-employment income, rental income, investment income, Social Security, unemployment, workers' comp. Some states deduct mandatory pre-tax items (FICA, mandatory retirement) before applying the formula. Means-tested benefits (SNAP, TANF, SSI) are typically excluded. Imputed income may apply to a parent who is voluntarily unemployed or underemployed.
Can child support be modified?
Yes. Either parent can request a modification if there is a 'substantial change in circumstances' — typically a 15-20% change in calculated support, job loss, significant medical issue, or change in custody schedule. Most states automatically review the order every 3 years for families receiving public assistance. File a modification motion with the court that issued the original order; do not unilaterally stop paying or you will accrue arrears.
What about college expenses?
Federal law does not require child support past 18 (or high-school graduation, whichever is later). About a third of states allow courts to order post-secondary support — New York, New Jersey, Massachusetts, Connecticut, Illinois, and Indiana are notable examples. The rest leave college costs to private agreement between parents. If college matters to you, address it in the divorce settlement or parenting plan rather than relying on the support order.