Child Support Calculator

Frequently Asked Questions

How is child support calculated?

About 40 states use the Income Shares model, which combines both parents' incomes and assigns a share based on each parent's percentage of the total. Other states use the Percentage of Income model (a percentage of the noncustodial parent's income) or the Melson formula. Adjustments are made for health insurance, childcare, and parenting-time overnights.

Can the calculated amount be changed?

Courts generally must follow the state guideline amount but can deviate for documented reasons such as extraordinary medical needs, private school tuition, very high or very low income, or shared custody arrangements with substantial overnights for both parents.

When can support be modified?

Most states allow modification when there has been a substantial change in circumstances - commonly a 15-20% income change, job loss, a new child, or a significant change in custody. Some states also allow review every 3 years regardless of changes. Modifications are not retroactive before the filing date.

What happens if support is not paid?

Enforcement tools include wage garnishment, tax-refund interception, license suspension (driver, professional, recreational), passport denial, liens, and contempt of court that can include jail time. Federal law also enables interstate enforcement under UIFSA.

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Legal Disclaimer: Information only. Not legal advice.

This calculator provides information for educational purposes only and does not constitute legal advice. Laws vary by jurisdiction and individual circumstances. Do not rely on this tool for legal decisions. Consult a licensed attorney in your jurisdiction for legal advice.

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How This Calculator Works

This estimator uses a percentage-of-income model resembling the older "Percentage of Obligor Income" standard still used in states like Texas and Wisconsin. It applies a per-child guideline rate to monthly income - 17% for one child, 25% for two, 32% for three, 40% for four, and 45% for five - then scales the obligation down by the share of time the other parent has the children (more custody for you means a smaller payment from you). Enter annual income, your custody percentage, and the number of children to see the estimated monthly and annual obligation.

Income Shares vs. Percentage Models

Roughly 40 states use the "Income Shares" model, which combines both parents' incomes, looks up a basic obligation on a state economic table, and prorates it by each parent's income share - a very different calculation than the single-parent percentage method here. A handful use the "Melson Formula." Because of this, the same family can owe materially different amounts in different states. Treat this figure as a rough national-style baseline, not your state's guideline output.

What This Calculator Leaves Out

Health insurance & medical: premiums and uninsured costs are usually added on top and split between parents.

Childcare: work-related daycare is typically a separate add-on, often a large one.

Income definition: courts count bonuses, overtime, self-employment income, and sometimes impute income to an underemployed parent.

Parenting-time adjustments: many states sharply reduce the obligation only above a threshold (e.g., 35%–40%) of overnights.

Caps and self-support reserves: low-income payors get a floor; very high incomes often trigger discretionary deviation.

Modification & Enforcement

Orders are not permanent. Most states allow review when income changes by a material threshold (often 10–20%) or after a set period. Until a court modifies the order, the original amount keeps accruing - informal "we agreed to less" arrangements create arrears. Enforcement tools include wage garnishment, tax-refund interception, license suspension, and contempt. Child support is generally not dischargeable in bankruptcy.

Common Mistakes to Avoid

Assuming 50/50 physical custody means zero support - an income disparity can still produce a payment.

Stopping payments unilaterally during a dispute instead of filing for modification.

Confusing child support with alimony - they are calculated separately and taxed differently.

Relying on this estimate in negotiations - use your state's official worksheet and consult a family-law attorney; guidelines vary by jurisdiction.

Frequently Asked Questions

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