A child support estimator applies your state’s statutory guideline to gross parental incomes, the number of children, and the custody arrangement to approximate a monthly obligation. States fall into two broad camps: most use an income-shares model, and a minority use a percentage-of-obligor-income model. This tool selects the right approach for the state you choose and produces a guideline-style estimate, including a shared childcare add-on.
Why state models produce very different numbers
The model a state uses has a large effect on the estimated obligation when the two parents’ incomes are substantially different. In a percentage-of-income state like Texas, the obligor’s income is the only variable in the base formula — the receiving parent’s income is irrelevant to the base obligation. In an income-shares state, both incomes matter: a receiving parent who earns more than the paying parent will see the paying parent’s obligation reduced, because the combined income is high and the obligor’s share is smaller.
This design difference reflects different policy philosophies. Percentage-of-income states prioritise simplicity and predictability. Income-shares states attempt to replicate what the children would have received in an intact household by considering the full household income picture.
How it works
In income-shares states the calculation combines both parents’ gross monthly incomes. A child-count percentage of that combined income approximates the total support the children would receive if the household were intact. Each parent’s obligation is their share of combined income times that total. The paying parent is the one with fewer custody overnights, and their transfer is reduced by a credit proportional to the share of overnights they already cover.
In percentage-of-income states the formula is simpler: a flat statutory percentage — for example Texas’s 20% for one child, 25% for two, rising to 40% for five or more — is applied to the obligor parent’s net resources only. The other parent’s income does not enter the base figure.
Income-shares: obligation = combined income share × guideline total, less an overnight credit. Percentage model: obligation = statutory percent × obligor income.
Example and notes
Two parents earn $4,000 and $2,000 gross monthly in an income-shares state with two children. Combined income is $6,000; a representative two-child rate yields a total obligation, split two-thirds to the higher earner. If that parent has the fewer overnights, their share — minus an overnight credit and plus their portion of childcare — is the estimated transfer.
Real guidelines layer in self-support reserves, health-insurance credits, extraordinary expenses, low-income adjustments, and judicial deviation. This estimator deliberately stays at the guideline-skeleton level so you can sanity-check a number before mediation — always confirm with your state’s official worksheet.
Factors that move the number in practice
Courts and official worksheets include several add-ons and adjustments that this tool approximates or omits:
- Health insurance premiums — the cost of adding the child to an employer health plan is typically added to the base obligation and split by income share.
- Self-support reserve — most states set a floor below which the obligor’s income cannot be reduced by support, protecting a minimum standard of living for the paying parent.
- Low-income adjustments — some states apply a reduced percentage at very low income levels.
- Extraordinary medical or educational expenses — large, documented costs beyond ordinary medical coverage are often shared separately.
- Tax treatment — child support payments are not tax-deductible for the payer and are not taxable income for the recipient under federal law, unlike alimony. The tax year in which each parent may claim the child as a dependent is a separate negotiation.
- Judicial deviation — a judge may depart from the guideline for compelling reasons documented in the order. This tool estimates what the guideline produces, not what a specific judge might award.