How Child Support Is Calculated by State 2026: Every State's Formula in Plain Language

Child support is one area of family law where the outcome is not purely up to a judge's discretion. Every state uses a formula, and that formula determines the baseline amount before any deviations are considered. But the formulas vary significantly across states, and the inputs the formula uses vary just as much. Understanding which model your state uses, what counts as income, and how parenting time affects the calculation will help you understand what to expect before you step into a courtroom or a mediator's office.

The Two Main Child Support Models Used in America

States use one of two primary calculation models, or a variation of them. The income shares model combines both parents' incomes to determine what the child's needs would cost in an intact household, then assigns each parent a proportionate share of that cost. About 40 states use this model. The percentage of income model simply takes a percentage of the paying parent's income based on the number of children, without factoring in the receiving parent's income at all. About 10 states use this simpler approach.

Texas uses the percentage of income model. For one child, the paying parent owes 20% of their net income. For two children, 25%. For three children, 30%, with an additional 5% per child up to 40% for five or more children. These percentages are calculated on net income after taxes, health insurance, and Social Security. California, on the other hand, uses an income shares model built into a complex formula that factors in both parents' incomes, parenting time percentages, and various add-on costs.

What Counts as Income for Child Support Purposes

Nearly every source of money counts as income for child support calculations. Wages, salary, overtime, tips, commissions, self-employment income, rental income, interest and dividends, Social Security benefits, disability benefits, workers compensation, and unemployment benefits all count. Courts look at gross income before most deductions, though the specific adjustments allowed vary by state. In income shares states, both parents' incomes are calculated and combined.

If a parent is voluntarily unemployed or underemployed, courts can impute income based on earning capacity. The court looks at the parent's education, work history, skills, and the local job market to determine what they could reasonably earn. A parent who quit a $70,000-per-year job and now claims to earn nothing will likely have income imputed at or near their prior earning capacity. Courts are generally skeptical of income drops that happen to coincide with the filing of a support case.

How Parenting Time Affects the Support Amount

Parenting time matters significantly in income shares states. The formula accounts for the fact that a parent who has the child 40% of the time is directly covering 40% of the child's daily expenses during their parenting time. States typically apply a parenting time credit or adjustment that reduces the paying parent's support obligation as their parenting time increases above a certain threshold. The credit often kicks in meaningfully around 30% overnight parenting time.

In California, parenting time is actually one of the most important variables in the formula. Even small changes in the percentage of time each parent has can significantly change the support amount. A parent going from 30% to 40% overnight parenting time can see their support obligation drop substantially depending on the income levels involved. This is why parenting time negotiations and financial negotiations in divorce are so closely linked. The two issues directly affect each other.

Add-On Expenses That Go Beyond the Base Amount

The base child support amount covers routine daily expenses for the child. Most states have mandatory or discretionary add-on costs that are handled separately. Health insurance premiums for the child are typically added to the base support and split proportionately between the parents based on their income. The parent who carries the child on their health insurance gets a credit for the premium they pay, and the other parent contributes their proportionate share.

Childcare costs related to work or job training are also typically added and shared proportionately. Uninsured medical expenses above a certain annual threshold are usually split 50-50 or in proportion to incomes. Extracurricular activities, private school tuition, and other extraordinary expenses may be ordered by the court or agreed upon by the parties, but they are handled separately from the base formula and require individual analysis.

When Courts Deviate From the Formula

Every state allows courts to deviate from the guideline support amount when applying the formula would be unjust or inappropriate under the circumstances. Common reasons for deviation include extraordinary medical expenses for a parent or child, travel costs associated with long-distance parenting time, a child's specific educational needs, a parent's very high or very low income that makes the formula produce an unreasonable result, and shared custody arrangements where both parents incur roughly equal direct expenses.

Judges are required to document their reasons when they deviate from the guideline amount. An upward deviation means the paying parent pays more than the formula suggests. A downward deviation means they pay less. Deviations are more common at income extremes, particularly when applying the formula would result in a support amount that leaves the paying parent unable to meet their own basic needs, or conversely, when the formula would provide far more to the receiving parent than the child actually costs.

How States Set Limits for High-Income Parents

Most state guidelines cap the income to which the formula applies. Beyond the cap, additional support may or may not be awarded at the court's discretion. Texas caps the formula application at $9,200 in monthly net income for purposes of the base percentage. A parent earning $30,000 per month does not automatically owe support on the full amount under the Texas formula. For one child, Texas formula child support is capped at $1,840 per month, with additional support potentially available based on the child's proven needs.

High-income cases often require evidence of the child's actual lifestyle and expenses rather than simple formula application. Private school tuition, travel expenses, activities, and other costs become relevant when parents have substantial income and the formula cap is reached. Use our child support calculator to estimate the amount in your state, and see our state-specific guide for Texas at how child support is calculated in Texas. If you need to modify an existing order, read our guide on how to modify child support.