Estimate Monthly Child Support
Last reviewed: January 2026
Estimate monthly child support using the income shares model based on both parents' incomes and custody. This calculator runs entirely in your browser — your data stays private, and no account is required.
Most U.S. states use either the "Income Shares" model (39 states) or the "Percentage of Income" model (9 states) to determine child support. The Income Shares model combines both parents' incomes, looks up the total support obligation from a state-specific table, then splits it proportionally based on each parent's share of the combined income.[1] Key factors beyond income include the number of children, healthcare costs, childcare expenses, and the parenting time split — many states reduce the obligation when the non-custodial parent has significant overnight time (typically 20%+ of overnights).[2] Child support orders can be modified when there is a substantial change in circumstances, such as job loss, income increase, or change in custody arrangement.[3] Use the Alimony Calculator to estimate spousal support alongside child support.
| Combined Income | Support Obligation | Non-Custodial Share (60/40) | Monthly Payment |
|---|---|---|---|
| $4,000/mo | $1,060 | 60% | $636 |
| $6,000/mo | $1,450 | 60% | $870 |
| $8,000/mo | $1,780 | 60% | $1,068 |
| $10,000/mo | $2,060 | 60% | $1,236 |
| $15,000/mo | $2,700 | 60% | $1,620 |
Child support calculations in the United States follow one of three primary models, each used by different states. The Income Shares model (used by approximately 41 states) bases support on the combined income of both parents, determining the total amount that would have been spent on the child if the family remained intact, then dividing this amount proportionally based on each parent's share of combined income. The Percentage of Income model (used by approximately 6 states, including Wisconsin and Texas) bases support on a fixed percentage of the non-custodial parent's income only. The Melson Formula (used by Delaware, Hawaii, and Montana) is a more complex variation that considers each parent's minimum living expenses before calculating support obligations.
Regardless of the model, most states consider several common factors: both parents' gross or net income, the number of children requiring support, healthcare and insurance costs, childcare expenses, educational costs, the parenting time arrangement (overnights with each parent), and any special needs of the child. Some states also consider the standard of living the child would have enjoyed if the parents had stayed together, existing support obligations to other children, and extraordinary expenses such as travel costs for visitation between distant locations. Support amounts are typically determined using state-specific guidelines that produce presumptive amounts — judges can deviate from guidelines when circumstances warrant, but must document reasons for the deviation.
Accurately determining income is often the most contentious aspect of child support proceedings. "Income" for support purposes typically includes wages, salaries, commissions, bonuses, overtime, tips, self-employment income, rental income, investment income, pension and retirement benefits, Social Security benefits, unemployment and disability benefits, workers' compensation, and spousal maintenance received. Some states also consider imputed income — the amount a parent could earn based on their education, skills, and work history — if a parent is voluntarily unemployed or underemployed to reduce their support obligation.
Self-employment income presents particular challenges because business owners have more control over reported income through business deductions, corporate structure, and timing of income recognition. Courts may examine personal expenses paid through the business, depreciation add-backs, lifestyle inconsistent with reported income, and cash transactions to determine the parent's actual earning capacity. For employees, income is typically verified through tax returns, W-2s, pay stubs, and employer verification. Courts can require full financial disclosure and may impose penalties for failure to provide accurate financial information or deliberate underreporting of income.
Child support orders are not permanent — they can be modified when a material change in circumstances occurs. Common grounds for modification include significant changes in either parent's income (typically a change of 15-20% or more), changes in the parenting time arrangement, changes in the child's needs (medical conditions, educational requirements), and changes in childcare or health insurance costs. Most states require that modifications be requested through the court or child support agency — parents cannot unilaterally change the support amount, even by mutual agreement, without court approval.
Enforcement of child support obligations is aggressive in the United States. Tools available to enforcement agencies include wage garnishment (automatic deduction from paychecks), interception of tax refunds, suspension of driver's licenses, professional licenses, and passports, reporting to credit bureaus, seizure of bank accounts and assets, liens on property, and contempt of court proceedings that can result in fines or imprisonment. The Federal Office of Child Support Enforcement facilitates interstate and international enforcement through the Uniform Interstate Family Support Act (UIFSA). Despite these enforcement mechanisms, approximately $34 billion in child support goes uncollected annually in the United States, affecting millions of children.
Child support typically continues until the child reaches the age of majority, which varies by state — 18 in most states, 19 in some (Alabama, Nebraska), and 21 in others (Mississippi, New York for certain circumstances). Support may extend beyond the age of majority for children with disabilities that prevent self-support, and some states allow courts to order contribution to college expenses. Emancipation events that may end support before the age of majority include marriage, military enlistment, and court-ordered emancipation based on financial independence.
Arrearages (past-due support) do not expire when the child reaches the age of majority — they remain enforceable debts that can be collected indefinitely in most states. Interest may accrue on unpaid support at rates set by state law, sometimes exceeding 10% annually. Parents who accumulate significant arrearages often find that the total owed, including interest, far exceeds the original support amounts. For this reason, parents experiencing financial hardship should seek modification promptly rather than simply stopping payments — the obligation continues to accrue regardless of ability to pay until a court orders otherwise. For related financial planning, see our Budget Calculator and Net Salary Calculator.
Since the Tax Cuts and Jobs Act of 2017, child support payments are neither tax-deductible for the paying parent nor taxable income for the receiving parent. This is a straightforward rule that eliminates the confusion that previously existed when alimony (which had different tax treatment) and child support were intermingled. The child tax credit ($2,000 per qualifying child as of recent tax law) is generally claimed by the custodial parent unless the custodial parent signs Form 8332 releasing the claim to the non-custodial parent — this allocation can be negotiated as part of the overall support agreement and may provide tax benefits to the higher-income parent that can be shared through adjusted support amounts.
See also: Alimony / Spousal Support Estimator · Budget Calculator · Childcare Cost Calculator
→ Every state uses a different formula. Most states use the income-share model (combining both parents' incomes to determine the child's "fair share"), while a few use percentage-of-income (fixed percentage of the non-custodial parent's income). This calculator provides a general estimate — check your state's guidelines for accuracy.
→ Gross income includes more than just salary. Courts typically count wages, tips, bonuses, commissions, overtime, self-employment income, rental income, investment returns, pension benefits, and sometimes imputed income if a parent is voluntarily underemployed.
→ Child support is not tax-deductible. Unlike pre-2019 alimony, child support has never been deductible for the payer or taxable for the recipient. This affects overall financial planning. See our Tax Calculator for after-support tax projections.
→ Modifications require a material change in circumstances. Job loss, significant income changes, remarriage (in some states), or changes in custody can justify a modification. Document everything and file through the court — informal agreements aren't enforceable. Use our Budget Calculator to plan post-order finances.
See also: Alimony Calculator · Budget Calculator · Tax Calculator · Childcare Cost Calculator