About the Child Support Calculator
This child support calculator estimates a monthly payment using the income-shares model, the approach most US states use. It adds both parents’ gross monthly incomes, estimates the basic cost of raising the children from that combined income, and splits it in proportion to what each parent earns. Childcare and the children’s health insurance premiums are shared the same way.
It is meant for separating parents, mediators and anyone renegotiating an existing order who wants a realistic starting number before using their state’s official worksheet. You can see how parenting time changes the amount: once the paying parent has the children for more than a set share of overnights, a shared-custody formula cross-credits each parent’s time.
This is a simplified model, not any state’s official worksheet. The basic obligation is a flat share of combined income: 17% for one child, 25% for two, 29% for three, 31% for four and 34% for five or more — the percentages in Wisconsin’s child support standard (DCF 150). Because each parent’s share of the combined amount equals that percentage of their own income, the result matches Wisconsin’s basic percentage standard for payers earning under $7,000 a month, and the shared-custody step uses Wisconsin’s 150% cost multiplier (Wisconsin applies it from 25% of overnights). It does not apply Wisconsin’s optional lower percentages above $7,000 a month, and true income-shares states use tables whose percentage falls as income rises, so expect official results to be lower at high incomes and to differ by state. Check your state’s guideline calculator before relying on the figure.
With the default inputs, the estimated monthly child support is $2,131.58. Change any value above to recalculate instantly.
How to use the child support calculator
- 1Enter both parents’ gross monthly incomes.
- 2Enter the number of children covered by the order.
- 3Enter the paying parent’s share of overnights and your state’s shared-custody threshold.
- 4Add monthly work-related childcare and the children’s health insurance premium.
- 5Read the monthly amount and check the worksheet table to see each step.
Formula and method
Under the income-shares model both incomes are combined and a schedule gives the basic amount parents at that income typically spend on the children. Each parent owes a share equal to their share of combined income (s₁ and s₂). The paying parent sends their share to the parent with primary custody, who is presumed to spend their own share directly.
When the paying parent’s overnights (t₁) exceed the shared-custody threshold, many states multiply the basic obligation by 1.5 to reflect duplicated costs in two homes, then each parent owes their share for the time the children spend with the other parent; the two amounts are netted. Childcare and the children’s health insurance are split by income share and added on, assuming the other parent pays them.
- Basic
- Combined income × schedule percentage for the number of children
- s₁, s₂
- Each parent’s share of combined income
- t₁
- Paying parent’s share of overnights
- AddOns
- Monthly childcare plus children’s health insurance
Worked examples
$6,000 and $3,500 incomes, two children, 20% overnights
Combined income is $9,500, so the basic obligation for two children is 25% = $2,375. The paying parent earns 63.2% of the total, giving $1,500 of basic support plus 63.2% of $1,000 in childcare and insurance ($631.58), for about $2,132 a month.
Shared custody: 40% overnights, one child
The basic obligation is 17% of $12,000 = $2,040, or $3,060 after the 1.5 shared-custody multiplier. The paying parent owes 2/3 × $3,060 × 60% = $1,224; the other parent owes 1/3 × $3,060 × 40% = $408. The net payment is $816 a month.
Equal incomes, three children, high childcare
Combined income of $10,000 gives a basic obligation of 29% = $2,900 for three children. Each parent’s share is 50%, so the paying parent owes $1,450 plus half of $1,500 in add-ons ($750), or $2,200 a month.
Frequently asked questions
How is child support calculated?+
About 40 states use the income-shares model: both parents’ incomes are combined, a state schedule sets the basic cost of the children at that income, and each parent pays in proportion to their income. Other states use a percentage of the paying parent’s income or the Melson formula.
Does shared custody reduce child support?+
Usually, once the paying parent has more than a threshold share of overnights (often 25% to 40%, depending on the state). Many states then multiply the obligation by 1.5 and credit each parent for the time the children spend with them, which can cut support sharply.
What income is used for child support?+
Most states start from gross income from all sources — wages, self-employment, bonuses, commissions, rental income and benefits — and may impute income to a parent who is voluntarily unemployed or underemployed. Some states use net income instead.
Until what age is child support paid?+
Typically until the child turns 18, or until high-school graduation (often up to 19). Some states allow support for college expenses, and support for a disabled adult child can continue indefinitely.
Is child support taxable?+
No. Child support payments are not deductible by the parent who pays them and are not taxable income for the parent who receives them under US federal tax law.
Results are general estimates and not legal advice. Laws vary by jurisdiction — consult a qualified attorney.