Child Support Calculator US Income Shares Model

Parent Information

State

Payor monthly gross income

Recipient monthly gross income

Number of children

Custody & Expenses

Payor overnight parenting time (nights/year)

Standard every-other-weekend is roughly 73 nights/year.

Monthly work-related childcare costs

Monthly child health insurance premium

Your Estimate

Basic support obligation

Payor income share

Estimated monthly support
$0

Annual total

Legal DisclaimerThis calculator uses simplified Income Shares model approximations. Child support guidelines vary significantly by state and your actual obligation may differ. This is for educational purposes only — not legal advice. Consult a qualified family law attorney in your state.

How Child Support Is Calculated in the United States

Child support in the United States is determined at the state level, not federally. Each state uses one of three primary models: the Income Shares Model (used by most states), the Percentage of Income Model, or the Melson Formula. Despite the variation, all states share the same goal: ensuring children receive financial support proportionate to what their parents would have provided if the family remained intact.

The Income Shares Model — used by roughly 40 states — combines both parents' gross incomes, looks up a total child support obligation from a state table, then divides it between parents in proportion to their individual incomes. The Percentage of Income Model (used in states like Texas and Wisconsin) applies a fixed percentage directly to the non-custodial parent's income regardless of the other parent's earnings.

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This calculator uses a blended estimate based on common state formulas. Because child support rules vary significantly by state, always verify your estimate against your specific state's guidelines or consult a family law attorney.

U.S. Child Support Formulas

Income Shares Model:
  Combined Support Obligation = Table lookup (combined income + # children)
  Each Parent's Share = Their Income / Combined Income x Total Obligation
  Non-Custodial Parent Pays their share to custodial parent

Percentage Model (e.g. Texas):
  Support = Non-Custodial Gross Income x State Percentage
  1 child: 20% | 2 children: 25% | 3: 30% | 4: 35% | 5+: 40%

Worked Example (Income Shares Model)

Worked Example

Non-custodial parent gross monthly income: $5,500

Custodial parent gross monthly income: $3,200

Combined gross monthly income: $8,700

State table obligation (2 children at $8,700): approximately $1,640/month

Non-custodial parent's income share: $5,500 / $8,700 = 63.2%

Non-custodial parent's base obligation: 63.2% x $1,640 = $1,036/month

Plus: Proportional share of childcare and healthcare add-ons

Result

Estimated base child support: ~$1,036/month (before add-ons)

Child Support Percentages by State Model

State / Model	Method	Notes
Income Shares (most states)	Both incomes determine total need	California, New York, Florida, Illinois, and ~35 others
Texas (% of income)	20% (1 child), 25% (2), 30% (3)	Capped at $9,200/mo net income for standard guideline amount
Wisconsin (% of income)	17% (1 child), 25% (2), 29% (3)	One of the simplest state models; no combined income table
Delaware (Melson Formula)	Most complex model	Sets a primary needs reserve before calculating obligation
Federal CCPA cap	50-65% of disposable income	Maximum that can be withheld through income withholding orders

Common Child Support Mistakes (U.S.)

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Using net income instead of grossMost state models start with gross income. States that use net income (a minority) have specific deduction rules — don't simply use take-home pay.

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Not accounting for custody arrangementParenting time significantly affects the support calculation in most states. More overnights with the non-custodial parent generally reduce the support obligation.

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Ignoring healthcare and childcare add-onsMost states add the cost of the children's health insurance premiums and work-related childcare costs to the base obligation, divided proportionately. These can be substantial.

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Failing to seek modification when income changesChild support orders don't automatically update. A substantial change in income (typically 10-15% depending on the state) is grounds for a modification motion. Failure to seek modification can result in large arrears.

Frequently Asked Questions

How is child support calculated in the United States?

Child support formulas vary by state but use two main models: Income Shares (used by ~40 states), which considers both parents' incomes, and Percentage of Income (used in some states like Texas), which applies a fixed percentage to the non-custodial parent's income. States also add childcare and health insurance costs.

Does parenting time affect child support?

Yes. Most Income Shares states reduce child support as the non-custodial parent's overnights increase, typically above a threshold of around 92 nights per year. Some states use a specific formula adjustment; others leave it to judicial discretion.

Can child support be modified after it is ordered?

Yes. Either parent can petition for modification when there is a substantial change in circumstances — typically a 10–15% change in the guideline amount, a significant income change, or a change in custody arrangements.

Is child support taxable in the US?

No. Under federal law, child support payments are not deductible by the payor and are not taxable income to the recipient.

Child Support Calculator — United States

How Child Support Is Calculated in the United States

Worked Example (Income Shares Model)

Child Support Percentages by State Model

Common Child Support Mistakes (U.S.)

Frequently Asked Questions

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Child Support Calculator — United States

How Child Support Is Calculated in the United States

Worked Example (Income Shares Model)

Child Support Percentages by State Model

Common Child Support Mistakes (U.S.)

Frequently Asked Questions

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