Child Support Calculator — All 50 States + DC
Estimate your monthly child support figure under your state’s guideline formula. This free calculator covers all 50 states plus the District of Columbia across the four models U.S. states use: income shares (about 42 jurisdictions), percentage of obligor (Texas, Wisconsin, North Dakota, Nevada, Mississippi, Alaska), the Melson formula (Delaware, Hawaii, Montana), and hybrid approaches with judicial discretion.
Pick your state and enter your details to see the guideline number along with your state’s modification threshold — useful whether you’re planning a new order or checking whether your current order is far enough out of guideline to support a modification petition.
Select your state and enter your details above to see the guideline figure.
This calculator provides an educational estimate based on a parameterized model of the formula each state publishes. The actual figure your court orders may differ — sometimes substantially — based on your state’s full guideline table, judicial deviations, deductions and add-backs unique to your case, imputed income findings, and case-specific factors a calculator cannot model.
No reliance. Nothing on this page constitutes legal advice. No attorney-client relationship is created by your use of this calculator. Numbers are provided as-is, without warranty of accuracy, completeness, or fitness for any particular purpose, including but not limited to any court filing or settlement discussion.
Before you act on a number, consult a licensed attorney in your state or contact your state’s child support agency. Most states publish their own official guideline worksheet; the result that worksheet produces — not this estimate — is what a court will use.
How Your State Calculates Child Support
Pick your state in the calculator above to see a state-specific breakdown of which guideline model applies, the modification threshold, and the parenting-time rules in your jurisdiction.
How Child Support Is Calculated in the United States
Every state’s child support guideline is grounded in federal regulations (42 U.S.C. § 667 and 45 CFR § 302.56), which require each state to publish a presumptive formula. States picked one of four models:
Income Shares Model (about 42 states + D.C.)
Both parents’ incomes are combined. The state’s guideline table sets what two parents at that combined income are presumed to spend on raising a child. Each parent contributes a share of that total proportional to their income. Adjustments for health insurance, work-related childcare, and parenting time are applied on top. Income-shares states include California, Florida, Illinois, New York, Ohio, Georgia, Pennsylvania, Michigan, North Carolina, and most others.
Percentage of Obligor Model (6 states)
Only the paying parent’s income matters. A flat percentage — varying by number of children — is applied to the obligor’s net or gross income. Texas, Wisconsin, North Dakota, Nevada, Mississippi, and Alaska use this model. Math is simpler. Modifications turn almost entirely on changes in the obligor’s income.
Melson Formula (Delaware, Hawaii, Montana)
A hybrid that protects each parent’s self-support reserve first, then sets a primary needs allowance per child, then applies a Standard of Living Adjustment from any remaining income. Three states use it.
Hybrid & Discretionary Layers
A handful of states layer significant judicial discretion on top of whatever base model they use. The guideline figure is a starting point, not the final word. Massachusetts, Rhode Island, and Kentucky give judges more room to deviate with written findings.
Compare Child Support Across States: The Four Models Side by Side
States differ in which guideline model they use, what income they look at, and how much of a gap triggers a modification. The table below summarizes the four model families.
| Model | States Using It | What Determines the Amount | Typical Modification Trigger |
|---|---|---|---|
| Income Shares | ~42 states + DC | Both parents’ combined income, prorated to each by income share, with adjustments for parenting time, health insurance, and childcare. | 10–20% gap between current order and new guideline, or a fixed dollar amount (often $50/month). Varies by state. |
| Percentage of Obligor | Texas, Wisconsin, North Dakota, Nevada, Mississippi, Alaska | A flat statutory percentage of the paying parent’s income, scaled by number of children. The receiving parent’s income generally does not enter the calculation. | Same general thresholds, applied to changes in the obligor’s income alone. |
| Melson Formula | Delaware, Hawaii, Montana | Each parent’s self-support reserve is protected first, then a primary needs allowance per child is set, then any remaining income produces a Standard of Living Adjustment. | Same general thresholds, but the protected reserve floor reduces volatility at lower incomes. |
| Hybrid / Discretionary | Massachusetts, Rhode Island, Kentucky, others | A base model (usually income shares) plus broad judicial discretion to deviate with written findings. | Court findings plus the underlying state’s percentage or dollar threshold. |
Pick your state in the calculator above for the exact statute citation, overnight threshold, and modification gap that applies to your jurisdiction.
Using This Calculator to Check a Modification
Most states require a substantial change in circumstances — usually a 10–20% gap between the current order and the guideline figure — before a court will modify a child support order. Some states also accept a “scheduled review” trigger every three years under 42 U.S.C. § 666(a)(10) without a substantial-change showing.
When a calculator estimate differs from an existing order by more than a state’s threshold, it may indicate the order is a candidate for review. The gap alone is not determinative; courts also look at what caused the change (involuntary versus voluntary), whether it is expected to continue, and how it interacts with other guideline factors.
Modifications are frequently denied not because the numbers fall short, but because the petition does not identify a statutory ground the court can act on. State statutes enumerate the recognized grounds for modification. The 50-state guide walks through, chapter by chapter, which grounds each state’s courts recognize and the structure of a clean petition.
Low-Income Protections & the Self-Support Reserve
Most states protect a minimum monthly income from being swept into a child support calculation. This protected amount is called the self-support reserve. It typically tracks 110–150% of the federal poverty guideline for a single adult and is adjusted periodically as the federal poverty line moves.
When an obligor’s documented income falls at or below the reserve floor, the standard guideline calculation does not apply. Most states drop to a flat low-income figure (often $50 to $80 per month, sometimes zero) until income rises above the reserve. Melson states (Delaware, Hawaii, Montana) build this protection into the formula directly. Income-shares states apply it as a deviation from the guideline schedule.
When documented income is near or below the federal poverty line, most state guidelines replace the standard formula with a flat low-income minimum, which is typically lower than the standard-formula result. The calculator does not currently apply the reserve floor automatically; a state’s child support agency can run the official worksheet that does.
Self-Employment & Variable Income
Self-employed parents and parents with irregular income face a different calculation than W-2 wage earners. Most states use net business income (the Schedule C bottom line, not gross receipts). Many states also add back personal expenses run through the business: a car lease used mostly for commuting, a phone plan that covers the family, a home-office deduction that does not reflect a real out-of-pocket expense.
When income is seasonal, commission-driven, or otherwise irregular, courts commonly average the last two or three years of tax returns rather than relying on a single recent month. A windfall year does not become the baseline; a slump year does not either.
If the parties disagree on a self-employed parent’s real income, courts have several tools to test the books: bank statement analysis, lifestyle audits, and depositions of the parent’s accountant. The official worksheet result depends on which income figure the court accepts as accurate.
Tax Treatment of Child Support
Child support is not deductible by the paying parent and is not taxable income to the receiving parent. This treatment is settled at the federal level under IRS Publication 504. It is also the structural difference between child support and post-2018 alimony. For divorce instruments executed after December 31, 2018, alimony is no longer deductible or taxable either, but child support has long been treated this way.
Which parent claims the child as a dependent on a tax return is a separate question. It is usually fixed by the court order, by a written IRS Form 8332 release, or, in the absence of either, by the IRS tiebreaker rules. The dependency claim does not change the child support figure; it affects only the parent’s individual tax filing.
Frequently Asked Questions
How accurate is this child support calculator?
For percentage-of-obligor states (Texas, Wisconsin, North Dakota, Nevada, Mississippi, Alaska), the math is exact — those states publish flat statutory rates. For income-shares and Melson states, the estimate uses a parameterized version of the underlying federal guideline and tends to land within ±15% of each state’s published worksheet output. The actual figure your court orders may differ further based on deviations, deductions, and case-specific findings.
Can a judge order a different amount than the calculator shows?
Yes. Courts apply the state’s own official guideline worksheet, not third-party calculators. A judge can also deviate from the worksheet itself with written findings — common deviation grounds include the child’s exceptional needs, a parent’s exceptional resources, an existing court order for other children, or extraordinary medical or educational expenses. The calculator gives an educational estimate so you can decide whether filing a modification petition is worth pursuing.
What’s the difference between income shares, percentage of obligor, and the Melson formula?
Income shares combines both parents’ incomes and proportions the total obligation between them; it is the dominant model in U.S. states. Percentage of obligor uses only the paying parent’s income times a flat statutory percentage, used in six states. Melson protects each parent’s self-support reserve first, then divides what remains; it is used in three states (Delaware, Hawaii, Montana).
Does parenting time (overnights) reduce child support?
In most states, yes — but only after the paying parent has more than a state-specific threshold of overnights per year. The threshold ranges from 0 overnights (some states use a continuous credit) to about 146 overnights (40%, used by Illinois and Pennsylvania). Below the threshold, parenting time often produces no formula credit at all.
What income counts? Gross or net?
It depends on the state. About half use gross monthly income (before taxes). The other half use net income (after taxes and required deductions). A few states use “adjusted” income with state-specific add-backs. The calculator shows the basis under the income field once you pick a state.
How much does my income have to change to modify child support?
Most states require either (a) a substantial change in circumstances — usually defined as a 10–20% gap between the current order and the new guideline figure, or a dollar-amount gap of $50 or more per month, or (b) the passage of three years since the last review under 42 U.S.C. § 666(a)(10). The calculator’s result page shows the threshold for the state you select.
Do I still pay child support with 50/50 custody?
Often yes. Equal parenting time does not automatically zero out child support in most states. When parents share overnights equally but earn different incomes, the higher earner typically pays the lower earner to equalize the child’s living standard across both households. A few states will offset down to zero when incomes are also roughly equal. The per-state explainer in the calculator above shows when your state’s parenting-time formula switches in and what threshold applies.
What is imputed income, and when can a court use it against me?
Imputed income is what the court treats you as earning even when your actual paycheck shows less. Courts can impute income to a parent who is found voluntarily unemployed or voluntarily underemployed (meaning the parent could earn more but chose not to). Common scenarios include quitting a higher-paying job, refusing available work in the parent’s field, or shifting to cash income. Imputation typically draws on recent earning history, qualifications, and local labor market data. Involuntary job loss (a layoff, medical disability, employer closure) is generally not grounds for imputation.
How is child support calculated if I’m self-employed?
Most states use net business income — the Schedule C bottom line, not gross receipts. Many states also add back personal expenses run through the business that do not reflect a real out-of-pocket cost: a car lease used mostly for commuting, a phone plan covering the family, a home-office deduction with no real overhead. For seasonal or commission-based income, courts commonly average two or three years of tax returns rather than relying on a single recent month.
What happens to child support if I lose my job?
Job loss does not automatically reduce a child support order. Until the court modifies the order, the original amount continues to accrue and unpaid amounts become arrears. A modification petition is generally required, and the income change typically must be shown to be substantial, involuntary, and expected to continue. Because most states modify support only prospectively from the petition date rather than retroactively to the date of job loss, the timing of filing is a factor practitioners commonly flag in this context.
Does my new spouse’s income affect child support?
As a general rule, no. A new spouse’s income is not factored into the child support calculation in most states. The court is calculating what the legal parents owe the child, not what the household has available. A new spouse’s income can become relevant indirectly — for example, when assessing ability to pay arrears or when applying a self-support reserve deviation — but it is not income for the underlying guideline formula.
Does having another child reduce what I pay for my first child?
It can, but not automatically. Most states recognize a “subsequent children” deduction or a “duty to support other children” adjustment, which reduces the income figure used for the existing support order. The reduction is generally smaller than the amount that would apply if the new child were the only child. A modification petition is required before the adjustment takes effect. Some states will not consider subsequent children when an existing order is being modified upward, only downward.
What happens to child support when a child turns 18?
In most states, child support for that child ends at age 18 or upon high school graduation, whichever comes later, generally not past age 19 or 19.5. A few states extend support if the child is still a full-time high school student or has special needs. Termination is often not administratively automatic; many states require a separate notice of termination or a final motion before the case is closed. Any unpaid arrears continue to be enforceable past the child’s age of majority.
Is child support tax deductible?
No. Child support is not deductible by the paying parent and is not taxable income to the receiving parent. This treatment is set at the federal level (IRS Publication 504). Which parent claims the child as a dependent for tax purposes is a separate issue, usually fixed by the court order or by an IRS Form 8332 release.
Coverage: All 50 States + D.C.
This calculator covers child support guideline formulas for every U.S. state and the District of Columbia:
Educational information only. Not legal advice. Not a substitute for a licensed attorney in your state. No reliance should be placed on the figure produced by this calculator for any court filing, settlement discussion, or financial decision.