What is the income shares model?

The income shares model combines both parents’ gross incomes and determines the total child-rearing cost based on published tables. Each parent’s share is proportional to their contribution to combined income. Most U.S. states use this approach.

What is the percentage-of-income model?

The percentage-of-income model applies a fixed percentage to the non-custodial parent’s gross income. The percentage increases with more children. It is simpler but does not account for the custodial parent’s income.

Does custody time affect child support?

Yes. Many states reduce child support when the non-custodial parent has substantial parenting time. This worksheet keeps custody time as a separate planning factor rather than baking in one jurisdiction’s rule.

Can child support be modified?

Yes. Either parent can request modification if there is a substantial change in circumstances such as job loss, significant income change, or changes in custody. Courts require proof of the material change.

Is child support tax-deductible?

No. Under current federal tax law, child support payments are neither deductible by the payer nor taxable income for the recipient. That is one reason the worksheet keeps support and alimony separate.

What income is included in the calculation?

Gross income generally includes wages, salary, bonuses, commissions, self-employment income, rental income, dividends, interest, pensions, and Social Security benefits. Some states also impute income if a parent is voluntarily underemployed.

Child Support Estimator

Compare simplified income-shares and percentage-of-income child support worksheets using monthly income and child count inputs.

Non-Custodial Monthly Income

Custodial Monthly Income

Number of Children

Calculation Model

Estimated Monthly Support

$1,250.00

Income Shares model

Estimated Annual Support

$15,000.00

Approximate calculation

Child Cost Factor

25%

For 2 child(ren)

Non-Custodial Share

62.5%

Of combined income

Estimates only. Actual amounts vary by state guidelines, deductions, and judicial discretion.

Planning notes, formulas, and examples

About the Child Support Estimator

Child support is usually set under state guidelines that look at both parents’ finances and the needs of the child. The exact worksheet rules vary by jurisdiction, so this calculator uses simplified comparison models instead of pretending to reproduce every state formula.

The page lets you compare a basic income-shares-style estimate with a percentage-of-income estimate. That makes it useful for planning and negotiation, but it is not a court order and it does not resolve guideline credits, deviations, or local rule differences.

When This Page Helps

Understanding potential child-support ranges helps both parents plan budgets and compare settlement scenarios. A worksheet is more useful when the assumptions are visible instead of buried inside a jurisdiction-specific guideline table.

How to Use the Inputs

Enter the non-custodial parent’s gross monthly income.
Enter the custodial parent’s gross monthly income.
Select the number of children.
Choose the calculation model (income shares or percentage-of-income).
Review the estimated monthly child support payment.
Adjust inputs to explore different scenarios.

Formula used

Income Shares Model: Combined Income = Parent A + Parent B; Support Obligation = Combined × Child Cost % (based on # children); Non-Custodial Share = Obligation × (Non-Custodial Income / Combined Income)

Percentage-of-Income Model: Support = Non-Custodial Income × Rate (1 child: 17%, 2: 25%, 3: 29%, 4: 31%, 5+: 35%)

This worksheet does not apply credits or deviations unless they are added manually through the inputs or a state-specific version of the calculator.

Example Calculation

Result: $1,250/month

Combined monthly income is $8,000. For two children the cost percentage is 25%, yielding $2,000 in total obligation. The non-custodial parent earns 62.5% of combined income, so their share is $2,000 × 0.625 = $1,250 per month.

Tips & Best Practices

State guidelines vary significantly - check your specific state’s formula before relying on the worksheet result.
Extraordinary expenses (medical, childcare, education) may increase obligations.
Income includes wages, bonuses, commissions, self-employment, and investment income.
Custody time percentage can adjust the final amount in many states.
Child support orders can be modified if income changes substantially.
Keep documentation of all income sources for court proceedings.

How Courts Determine Child Support

Family courts follow statutory guidelines that establish presumptive support amounts. Judges may deviate from the guidelines for specific circumstances such as extraordinary medical needs, private school tuition, or travel expenses for visitation.

Income Shares vs. Percentage Models

The income shares model is considered more equitable because it accounts for both parents’ financial capacity. The percentage-of-income model is simpler to administer but can produce inequitable results when parents have disparate incomes.

Enforcement and Compliance

Child support orders are enforceable through wage garnishment, tax refund interception, license suspension, and contempt proceedings. The Federal Office of Child Support Enforcement coordinates interstate collection efforts.

Sources & Methodology

Last updated: March 28, 2026

Methodology

This worksheet compares two simplified child-support models: an income-shares-style estimate and a percentage-of-income estimate. It uses the entered monthly incomes and the number of children to apply a rough cost factor, then shows a monthly and annual support estimate so users can compare scenarios.

The page is intentionally conservative. It does not calculate guideline adjustments, deviations, imputed income, health-insurance credits, childcare credits, or court-specific parenting-time offsets unless they are explicitly represented in the worksheet inputs. It is a planning aid, not a live guideline determination.

Sources

Child support (Legal Information Institute, Cornell Law School) — General legal overview describing how child-support amounts vary by state and depend on both parents’ financial circumstances.
2023 Child Support: More Money for Families (Administration for Children and Families, Office of Child Support Enforcement) — Federal child-support overview showing that support amounts are set under state guidelines and income-based approaches.

Frequently Asked Questions

The income shares model combines both parents’ gross incomes and determines the total child-rearing cost based on published tables. Each parent’s share is proportional to their contribution to combined income. Most U.S. states use this approach.