The average child support payment in the United States was about $671 per month as of 2023, according to Census Bureau data, but that figure hides a wide spread.1U.S. Census Bureau. Child Support Received: 2023 How much child support runs for one kid depends on your state’s formula, both parents’ incomes, how custody is split, and whether the child has costs beyond the basics. A parent earning $40,000 a year might owe a few hundred dollars a month. A parent earning $150,000 could owe well over a thousand. The sections below walk through how the number is actually built.
How Your State’s Formula Sets the Number
Every state uses one of three models, and which one applies matters more than most parents realize.
Forty-one states use the Income Shares Model. It combines both parents’ incomes to estimate what the child would have received in an intact household, then splits that cost between parents in proportion to each one’s share of the total.2National Conference of State Legislatures. Child Support Guideline Models If you bring in 60% of the combined income, you cover roughly 60% of the child’s support obligation.
Six states use the Percentage of Income Model, which ignores the custodial parent’s earnings and sets support as a percentage of the noncustodial parent’s income. For one child, the typical rate falls between 17% and 25%. The percentage can be flat across income levels or slide downward as income rises.2National Conference of State Legislatures. Child Support Guideline Models
The remaining three states use the Melson Formula, a more detailed version of Income Shares that first sets aside enough income for each parent to cover their own basic living expenses before calculating the child’s share.
What the Math Looks Like for One Child
In an Income Shares state, both parents’ incomes are added together. The state’s guideline table maps that combined figure to a presumed monthly cost of raising one child at that income level. Each parent’s share is proportional.
A simplified example: combined income of $80,000 a year. The state table might put the basic obligation for one child at $800 per month. The noncustodial parent earns $50,000 and the custodial parent earns $30,000, so the noncustodial parent’s share is 62.5% of the combined income, or about $500 per month. The custodial parent’s $300 share is assumed to be spent directly on the child in the home.
In a Percentage of Income state, the math is simpler. If the rate for one child is 20% and the noncustodial parent earns $4,000 per month, the obligation is $800 regardless of the other parent’s income.
Most states publish free online calculators. Plug in both incomes, the custody arrangement, and insurance costs to get a preliminary estimate before you set foot in a courtroom.
What Pushes the Number Up or Down
Income
Income is the biggest single variable. Courts define it broadly: wages, salary, commissions, bonuses, self-employment earnings, rental income, and royalties all count. So do workers’ compensation, unemployment, disability, and spousal support from a previous relationship. The starting point is gross income, though most formulas subtract mandatory deductions like income taxes and union dues to reach a net figure.
If a parent is voluntarily unemployed or working below their earning capacity to keep the number low, courts can impute income. The judge calculates what the parent should be earning based on education, work history, skills, and the local job market, then plugs that figure into the formula. It’s a common tactic and it almost never works.
Parenting Time
How much time the child spends with each parent directly affects the calculation. In most states, once the noncustodial parent’s overnight time crosses a threshold, the formula adjusts downward because that parent is covering more day-to-day costs directly. Thresholds commonly sit somewhere between 20% and 30% of annual overnights, depending on the state. Every other weekend and one weeknight probably won’t meet it. A true 50/50 schedule almost certainly will.
The adjustment isn’t dollar-for-dollar. Even in a 50/50 split, the higher-earning parent usually still owes some support so the child maintains a comparable standard of living in both homes.
Add-On Expenses
The base number covers housing, food, and clothing. Certain other costs are handled separately and split between parents in proportion to income:
- Health insurance premiums for the child, usually carried by whichever parent has better employer coverage.
- Out-of-pocket medical costs including co-pays, deductibles, and procedures not fully covered.
- Work-related childcare such as daycare, after-school programs, or babysitting that lets a parent stay employed.
- Special needs or education costs like tutoring, private school tuition, or therapy when documented.
Add-ons can push the total well past the base figure. A child with braces, weekly therapy, and full-time daycare can add several hundred dollars a month.
When a Judge Deviates from the Formula
State guidelines produce a presumptive amount, not a fixed one. A judge can deviate when applying the formula would produce a result that doesn’t fit the family, but the court has to explain on the record why. Common reasons:
- Very high combined income, where the formula produces an amount that exceeds any reasonable estimate of the child’s needs. Courts have discretion to cap or adjust.
- Significant medical or educational needs beyond what the standard add-ons cover.
- Other dependents. A paying parent supporting children from another relationship may qualify for a downward adjustment.
- Parental agreement. Parents can agree to a different amount, subject to court approval so the child isn’t shortchanged.
Most states also build in a self-support reserve, a minimum income the paying parent keeps before any obligation kicks in, typically tied to the federal poverty guidelines. If income falls below the reserve after calculation, the court reduces the order or sets a nominal minimum, sometimes as low as $50 per month.
Changing the Amount Later
Child support orders aren’t permanent. Either parent can request a modification when circumstances change significantly. Qualifying changes generally include job loss, a substantial increase or decrease in either parent’s income, a shift in the custody arrangement, a new disability, incarceration, or military deployment. Many states allow modification when recalculating the formula would change the existing order by at least 20% or $50, whichever is less.
The key word is “substantial.” A small raise or a minor shift in expenses won’t justify a new order. But courts can only change support going forward from the date you file the modification request. Waiting means you’re stuck with the old amount for every month you delay.
What Happens If Payments Stop
Federal law requires every state to maintain a set of enforcement tools, and they’re more aggressive than most people expect.3Office of the Law Revision Counsel. 42 USC 666 – Requirement of Statutorily Prescribed Procedures to Improve Effectiveness of Child Support Enforcement
- Automatic wage withholding. Employers deduct support directly from the paying parent’s paycheck. This isn’t triggered by missed payments; it’s the default for new and modified orders.
- Garnishment limits. Federal law caps wage garnishment at 50% of disposable earnings if the parent is supporting another spouse or child, or 60% if not. Those limits rise to 55% and 65% when payments are more than 12 weeks overdue.4Office of the Law Revision Counsel. 15 USC 1673 – Restriction on Garnishment
- Tax refund intercept. State agencies can seize federal and state refunds to cover arrears.
- License suspension of driver’s, professional, or recreational licenses.
- Passport denial once arrears exceed $2,500.5Office of the Law Revision Counsel. 42 USC 652 – Duties of Secretary
- Contempt of court, which carries potential jail time of up to 180 days in some jurisdictions.
Arrears accumulate interest in many states, and courts almost never forgive past-due amounts retroactively. If you can’t keep up, filing for a modification immediately is the only way to stop the balance from growing.
Getting a Realistic Estimate for Your Situation
The USDA estimated that a middle-income, married-couple household spends roughly $13,000 per year per child on food, shelter, and other necessities, and that figure is several years old.6U.S. Department of Agriculture. The Cost of Raising a Child Adjusted for inflation, the real number is higher, and it climbs further in regions with expensive housing or childcare. Guideline formulas are built on similar economic data, which is why the calculator’s output often feels high to the paying parent and low to the receiving parent.
To get a realistic number, find your state’s child support calculator online or contact your state’s child support enforcement agency. You’ll need your gross income, the other parent’s gross income, the proposed custody schedule, health insurance premiums for the child, and any recurring childcare costs. The result will be close to what a judge would order. It won’t include add-ons or potential deviations, but it gives you a baseline to plan around.