Combined income, split by parent
Support is shared in proportion to each parent's income.
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Child Support Calculator
Estimate a monthly child support obligation with the income shares model used by most US states, based on both parents' incomes, the number of children, and parenting time.
Estimated monthly support
$0
Combined income—
Basic obligation—
Paying parent's share—
Parenting-time credit—
How the income shares model works
Most US states use the income shares model. The idea is to estimate what the parents would have spent on the children if they still lived together, then divide that "basic obligation" between them in proportion to their incomes. The parent with less parenting time typically pays their share to the other parent, reduced by a credit for the overnights they cover directly.
The formula
combined income = parent A + parent B
basic obligation = combined income × child factor
paying parent's share = basic obligation × (A ÷ combined)
support = share − (share × overnights ÷ 365)
basic obligation = combined income × child factor
paying parent's share = basic obligation × (A ÷ combined)
support = share − (share × overnights ÷ 365)
Child factors used here (share of combined income): 1 child ≈ 20%, 2 ≈ 28%, 3 ≈ 33%, 4 ≈ 37%, 5 ≈ 40%.
Worked example
Paying parent earns $5,000 and the other $3,000 (combined $8,000) with 2 children. The basic obligation is 28% ≈ $2,240; the paying parent's income share is 62.5% ≈ $1,400. With 90 overnights, a credit of about $345 lowers the estimate to roughly $1,055/month.
Frequently asked questions
What is the income shares model?
It estimates what parents would have spent on a child together, then splits it by income share.
Is child support the same in every state?
No, each state has its own formula and tables; this is a simplified estimate.
How does parenting time affect it?
More overnights for the paying parent usually lower the obligation.
Does this include alimony?
No, spousal support is a separate calculation.
Can I rely on this in court?
No, use your state's official worksheet and consult an attorney.