What Child Support Costs for One Child: State Ranges and How Courts Calculate It

Child support for one child varies by state and income, but most states calculate it between 17% and 25% of the paying parent's gross income

There is no single dollar amount that applies everywhere. A parent earning $40,000 a year in one state might pay $340 monthly for one child, while the same income in another state could mean $500 monthly. The difference comes down to how each state's formula works, what counts as "income," and whether other children or support obligations exist.

Most states use one of two methods: the income shares model (used by about 40 states) or the percentage of income model (used by about 10 states). A handful of states use a hybrid. Understanding which model your state uses and what income counts toward the calculation helps you predict what a court might order.

Key Takeaways

• Child support for one child typically ranges from 17% to 25% of the paying parent's gross income, but the exact amount depends on your state's formula and both parents' incomes.
• The income shares model (most common) calculates what two parents would spend on a child if they lived together, then splits that cost based on each parent's income percentage.
• Income usually means wages and salary, but also includes self-employment income, bonuses, rental income, and sometimes unemployment or disability benefits.
• A court can adjust the standard amount if one parent has other children to support, pays health insurance for the child, or if the paying parent's income is very high or very low.
• Child support orders change only when there is a significant change in income or custody, not automatically when a child turns a certain age.

How the income shares model calculates one child's support

Under the income shares model, a court first adds both parents' gross incomes together. Then it looks up a table (called a guideline table) that shows what two parents living together would typically spend on one child at that combined income level. That combined amount is the basic child support obligation.

Next, the court divides that obligation between the parents based on each parent's share of the total income. If one parent earns 70% of the combined income and the other earns 30%, the first parent pays 70% of the obligation. The parent with primary custody usually does not write a check; instead, the other parent's payment is treated as satisfying their share.

Example: Combined income is $60,000. The guideline table says two parents spend $1,200 monthly on one child. Parent A earns $42,000 (70%) and Parent B earns $18,000 (30%). Parent A pays 70% of $1,200 = $840 monthly. Parent B's 30% share ($360) is assumed to be spent directly on the child in the home, so Parent A sends $840 to Parent B.

How the percentage of income model works

States using the percentage of income model skip the combined table and instead explore a flat percentage directly to the paying parent's income. The percentage varies by state and sometimes by number of children, but for one child it commonly ranges from 17% to 22% of gross income.

This model is simpler to calculate but does not account for what the other parent earns. A parent paying support under this model pays the same percentage whether the receiving parent earns $20,000 or $120,000 annually.

Example: State uses 20% for one child. Paying parent earns $50,000 gross. Child support = $50,000 × 0.20 = $10,000 yearly, or about $833 monthly.

What counts as income for child support

Income is broader than just a paycheck. Courts typically include wages, salary, bonuses, commissions, self-employment income, rental income, interest and dividend income, and income from retirement accounts or pensions. Some states also count unemployment benefits, workers' compensation, and disability payments.

Income usually does not include public information (like TANF or SNAP), tax refunds, or money from selling an asset. Courts also typically exclude the income of a new spouse or partner, though they may consider it if the paying parent is deliberately underemployed.

If you are self-employed, the court uses net income (revenue minus legitimate business expenses), not gross revenue. You will need tax returns and business records to prove what you actually earned.

Adjustments that change the standard amount

The guideline amount is a starting point, not a ceiling. Courts can order more or less than the guideline if certain circumstances exist. Common reasons for adjustment include:

• The paying parent has other children from other relationships and is already paying support for them.
• One parent pays for the child's health insurance, and that cost is significant.
• One parent has primary custody more than 50% of the time (shared custody can lower the paying parent's obligation).
• The paying parent's income is very high (above the state's guideline cap, which varies by state but often ranges from $150,000 to $300,000).
• The paying parent's income is very low or zero, and they cannot meet the guideline amount.
• Either parent has substantial childcare costs or unreimbursed medical expenses for the child.

A court must state in writing why it is deviating from the guideline if it does so. This written explanation is important because it becomes part of the order and affects how future modifications are handled.

How income changes affect child support

Child support does not automatically change when a child has a birthday or when a new school year starts. An order stays in place until a court modifies it. To change the amount, one parent must file a motion showing a substantial change in circumstances.

A substantial change usually means the paying parent's income has gone up or down by a certain percentage (often 10% to 15%, depending on the state) or by a set dollar amount. A job loss, a significant raise, a promotion, or a reduction in hours can trigger a modification. So can a change in custody.

The parent seeking the change files paperwork with the court (or with the state's child support enforcement agency if the order is being enforced by the state). The other parent then has a chance to respond. If both parents agree to the new amount, the court can approve it quickly. If they disagree, a judge holds a hearing.

State-by-state variation in child support amounts

Because states set their own guidelines, the same income produces different support amounts in different places. A parent earning $50,000 annually might pay roughly $425 monthly in one state but $600 monthly in another, all for one child with no other complications.

Factors that vary by state include the percentage used (in percentage-of-income states), the guideline table amounts (in income-shares states), what counts as income, how high the cap is for very high earners, and how much weight the court gives to shared custody. Some states also update their guidelines every few years to reflect inflation and changing spending patterns, while others update less frequently.

If you are moving to a different state or the other parent is, the child support order can usually be transferred to the new state's court system. However, the amount may change if the new state's guidelines are different.

Frequently Asked Questions

Does child support stop when the child turns 18?

In most states, yes, but not automatically. The order ends on the date specified in the court order, which is often the child's 18th birthday or high school graduation, whichever comes later. Some states extend support through age 19 or 20 if the child is still in high school. The paying parent does not need to file anything; the order straightforward expires. However, if the child is still in school past 18, the receiving parent may need to file paperwork to extend support.

What if the paying parent loses their job?

Child support does not automatically stop or reduce. The paying parent must file a motion to modify the order and show the job loss and new income (or lack of income). Courts generally do not reduce support to zero unless the parent is truly unable to work. Unemployment benefits, if received, usually count as income. If a parent deliberately quits to avoid paying support, a judge may order support based on what they could earn, not what they actually earn.

Can child support be different if parents share custody equally?

Yes. When both parents have the child roughly 50% of the time, the paying parent's obligation often decreases because they are already spending money on the child during their parenting time. Some states reduce the guideline amount by a percentage; others recalculate the entire obligation. The exact reduction depends on your state's rules and the specific custody schedule.

What if the paying parent earns much more than the guideline cap?

States set a cap on income used in the guideline calculation (often $150,000 to $300,000 annually), but this does not mean high earners pay nothing on income above the cap. A judge has discretion to order support on the excess income, considering the child's standard of living, the parents' ability to pay, and other factors. There is no fixed formula for income above the cap, so outcomes vary.

Can I negotiate a different amount than what the guideline says?

Yes, but only if both parents agree in writing and a judge approves it. Parents can agree to pay more or less than the guideline, but the court must find that the agreement is in the child's best interest and that both parents understand what they are agreeing to. A written agreement that a judge has signed is enforceable; a handshake agreement is not.