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Quick answer
Child support is calculated using your state's guidelines, which fall into one of three models: Income Shares (used by about 40 states), Percentage of Income (used by about 11 states), or the Melson Formula (used by Delaware, Hawaii, and Montana). The base amount is then adjusted for custody time, healthcare costs, childcare, and other add-ons. Use the free estimator below to get an instant national estimate based on your specific situation.
Child support is one of the first financial questions that comes up in a divorce or separation involving kids. The number matters to everyone: the parent who will be paying wants to know what to expect in their budget, and the parent who will be receiving wants to know whether it will actually cover what their children need. Our free child support calculator below gives you an instant national estimate based on your state's guidelines, both parents' incomes, your custody arrangement, and common add-on expenses. Use it as your starting point, then read on to understand exactly how courts arrive at a final number.
Use the free child support calculator
Enter a few details above and get your estimate instantly. The calculator covers all 50 states, identifies which calculation model your state uses, and accounts for common add-on expenses that courts regularly include in final orders. No personal information is collected or stored.
Important
This calculator provides an educational estimate only. It does not account for judicial discretion, imputed income, county-level variations, or income outside the standard schedule range. The actual amount ordered by a court may be higher or lower.
How child support is calculated: the three national models
Every state uses a statutory formula to determine child support. Federal law requires all states to have written guidelines, but each state chose its own model when drafting them. There are three models currently in use across the country, and understanding which one applies in your state is the first step to making sense of any estimate you receive.
Income Shares model (about 40 states)
Used by states including California, Florida, New York, and Ohio, the Income Shares model combines both parents' gross monthly incomes to estimate how much the couple would have spent on the children if the family had stayed together. Each parent then pays their proportional share of that total obligation. Because it considers both parents' earnings, this model is sensitive to income changes on either side.
Percentage of Income model (about 11 states)
Used by states including Wisconsin, Minnesota, Tennessee, and Texas, this model applies a fixed percentage of only the paying parent's gross income based on the number of children. The receiving parent's income is not factored in at all. It is simpler to apply, and the obligation changes only when the paying parent's income changes.
Melson Formula (Delaware, Hawaii, and Montana)
The most nuanced of the three, the Melson Formula first reserves a minimum amount for each parent to cover their own basic living needs before allocating anything to the children. The remaining income is then split proportionally. It tends to produce lower base amounts for parents at or near a subsistence income level.
How the calculator identifies your state's model
When you select your state in step one of the calculator, a model badge appears automatically confirming which formula applies to your estimate. Percentage of Income states only require the paying parent's income; the receiving parent's income field is dimmed and not required for those states.
If you are unsure whether your state's guidelines have been updated recently, your state's child support enforcement agency website is the authoritative source for the current schedule.
Factors that affect the actual amount a court orders
A guideline calculation gives you a baseline, but the number a judge signs off on can be higher or lower depending on the specifics of your family's situation. Courts in every state have the authority to deviate from the guideline amount when a strict application would be unjust or inappropriate.
Custody and parenting time
The more time the paying parent spends with the children, the lower the guideline obligation tends to be. A 50/50 custody arrangement typically produces a meaningfully lower payment than a 100/0 arrangement because the costs of raising the children are shared more directly between households. The calculator's custody selector lets you model different split scenarios side by side.
Healthcare and childcare add-ons
Courts commonly add the monthly cost of health insurance for the children on top of the base support amount. Work-related childcare costs, including daycare and after-school programs the custodial parent needs in order to work, are also added regularly. Each parent typically pays their proportional share of these expenses based on their income ratio.
Special or extraordinary needs
Children with significant medical conditions, disabilities, or educational needs may require additional support beyond what the base formula accounts for. Courts have broad discretion here and can order amounts well above guideline when the child's circumstances warrant it.
Imputed income
If a court finds that a parent is voluntarily unemployed or working below their actual earning capacity to reduce their support obligation, it can assign (impute) a higher income level to that parent and calculate support from there. Courts look at the parent's education, work history, job market, and available opportunities when making this determination. Imputation is a judicial call that cannot be captured in an online calculator. If this is likely to be a factor in your case, it warrants a professional conversation before you enter court. You can learn more about financial issues that arise when children are involved in a divorce in our dedicated guide.
What counts as income for child support purposes
State guidelines cast a wide net when defining income. Most parents are surprised by how much is included. The calculator uses gross monthly income (before taxes) because that is the figure most state formulas require.
What is typically included
Wages, salary, and self-employment income are the starting point. Beyond that, courts typically also count bonuses, commissions, and overtime (averaged over 12 to 24 months rather than treated as one-time windfalls), Social Security and disability benefits, veterans' benefits, rental income, investment income and interest, and alimony received from a prior relationship. If a parent receives Social Security dependent benefits on behalf of the children specifically, many states allow those payments to offset part of the support obligation directly.
What is typically excluded
Means-tested public assistance such as Supplemental Security Income (SSI) is generally excluded. Child support you receive for children from a prior relationship is also typically not counted as income, though existing child support you pay for other children may reduce your available income figure in some states.
A word on financial disclosure
Both parents are required to provide complete financial disclosure during a divorce or support proceeding. Attempting to hide income or voluntarily reduce earnings to lower a support obligation almost always backfires. Courts use subpoenas, bank record analysis, and forensic accounting to find income that is not being disclosed. The consequences range from an adverse inference in the proceedings to sanctions and attorney fee awards.
If your income is variable, self-employed, or structured in an unusual way, an average over the most recent 12 to 24 months is the standard approach courts use to arrive at a representative figure.
How to modify a child support order
A child support order is not permanent. All states allow either parent to request a modification when there has been a substantial change in circumstances since the original order was entered. The most common qualifying events include a significant income change for either parent, a job loss, a change in the custody arrangement, a child aging out of support, or a major shift in the child's needs.
Most states also conduct automatic periodic reviews, typically every three years, through the state's child support enforcement agency. You can request one of these reviews without having to file a motion in court, which makes it the lowest-cost path when the change in circumstances is straightforward.
One thing that does not change the order on its own: a verbal agreement between the parents to pay less. Courts only recognize written, court-approved modifications. If you agree to informal changes and the other parent later claims you owe the original amount, you will owe it, plus any arrears that have accumulated. Financial agreements need to go through the proper legal channels. If you believe a modification is warranted, create a free Hello Divorce account to start organizing your financial information, or schedule a free 15-minute call to talk through your options first.
Have questions about child support in your divorce?
Our team includes family law professionals who can review your situation, explain your state's guidelines in plain language, and help you understand what a realistic outcome looks like.
Schedule your free 15-minute callFrequently asked questions
How accurate is this child support calculator?
The calculator produces an educational estimate based on published state guidelines, USDA cost-of-child-rearing data, and the income and custody information you enter. It does not account for judicial discretion, imputed income, county-level variations, prior support orders, or income that falls outside the standard schedule range. Treat the result as a planning figure, not a legal prediction. The actual amount ordered by a court may be higher or lower.
Does child support cover only basic living expenses?
The base guideline amount is designed to cover a child's basic needs, including housing, food, and clothing. Courts regularly add separate amounts on top of the base for healthcare insurance, work-related childcare, and sometimes education or extracurricular activities. These add-on amounts are legally enforceable once the order is entered, just like the base support itself.
Can parents agree on a child support amount without going to court?
Yes, but only up to a point. Parents can negotiate and agree on a number. However, if that number is below the state guideline amount, a judge must approve it and will want to understand why deviating from the guidelines is in the child's best interests. A court will not simply approve a below-guidelines agreement without explanation. If both parents agree on an above-guidelines amount, courts are generally more willing to sign off without scrutiny.
What happens if the paying parent stops paying child support?
Unpaid child support (called arrears) accumulates with interest in most states and does not disappear. Enforcement mechanisms include wage garnishment, interception of tax refunds, suspension of driver's and professional licenses, bank account levies, and in serious cases, contempt of court charges that can result in jail time. State child support enforcement agencies can also assist at no cost to the recipient.
Is child support taxable income for the parent who receives it?
No. Child support is neither taxable income for the parent who receives it nor tax-deductible for the parent who pays it. Under current federal tax law for divorce agreements finalized after 2018, spousal support is also neither deductible nor taxable. If your divorce agreement predates 2019, the rules for spousal support may differ and are worth confirming with a tax professional.
Until what age does a parent pay child support?
In most states, child support continues until the child turns 18 or graduates from high school, whichever is later. A handful of states extend the obligation to age 19 or 21. Support may end earlier if a child legally emancipates, enters the military, or gets married before the cutoff age. A small number of states can require contributions toward college expenses under certain circumstances, but this is not universal.
Does remarriage affect child support?
In most states, a parent's remarriage does not automatically change a child support obligation. A new spouse's income is generally not counted as the parent's income for support purposes. However, if remarriage leads to a substantial improvement in a parent's financial circumstances and the other parent can demonstrate a material change, they may have grounds to request a modification review. The remarriage of the receiving parent does not typically reduce the paying parent's obligation on its own.
References & further reading
Sources cited in this article and recommended for further reading.
- 1. U.S. Department of Health and Human Services. "Child Support Handbook" — Overview of federal child support law, state guideline requirements, and enforcement mechanisms. HHS Office of Child Support Services, 2024. Accessed April 2026.
- 2. USDA Economic Research Service. "Expenditures on Children by Families" — Annual report on the cost of raising a child from birth to age 17, used as the basis for many state income-shares guideline schedules. USDA, 2017. Accessed April 2026.
- 3. California Department of Child Support Services. "Guideline Calculator" — Official state calculator illustrating the income shares model. CA DCSS. Accessed April 2026.
- 4. Internal Revenue Service. "Topic No. 452: Alimony and Separate Maintenance" — IRS guidance confirming child support is neither deductible for the payer nor taxable income for the recipient. IRS.gov. Accessed April 2026.
- 5. Hello Divorce. "Special concerns for divorce with minor children" — Guide to the financial and legal considerations in divorces involving children. Hello Divorce. Accessed April 2026.
- 6. Hello Divorce. "How to talk to your kids about divorce" — Guidance on co-parenting communication after separation. Hello Divorce. Accessed April 2026.