Source: U.S. Census Bureau. Actual amounts vary widely by state, income level, and custody arrangement. Use our state calculators for an accurate estimate.
The Three Child Support Models in the United States
Every U.S. state uses one of three mathematical models to calculate child support. The model determines whose income matters and how the obligation is computed. Understanding which model your state uses is the first step in estimating your child support.
Income Shares (41 States)
Both parents' incomes are combined. The child's "cost" is looked up from a state schedule. Each parent pays their proportional share. Used by the majority of states including CA, FL, OH, NY, IL, PA, NC.
Percentage of Income (6 States)
Only the non-custodial parent's income is used. A flat percentage is applied: typically 17-25% for one child, scaling up for more children. Used by TX, WI, MS, ND (and variations in a few others).
Melson Formula (3 States)
A modified income shares approach that first ensures each parent can meet their own basic needs (self-support allowance), then allocates remaining income. Used by DE, HI, MT.
Percentage of Income Model: Step-by-Step
The Percentage of Income model is simpler: it uses only the non-custodial parent's income and applies a fixed percentage based on the number of children.
Step 1: Determine the Obligor's Income
Calculate the non-custodial parent's monthly income. In Texas, this is "net resources" (gross income minus taxes, Social Security, Medicare, children's health insurance, and union dues). In Wisconsin, it's gross income.
Step 2: Apply the Guideline Percentage
Typical percentages (using Texas as the example):
| Number of Children | Texas (Net) | Wisconsin (Gross) | Mississippi |
|---|---|---|---|
| 1 child | 20% | 17% | 14% |
| 2 children | 25% | 25% | 20% |
| 3 children | 30% | 29% | 22% |
| 4 children | 35% | 31% | 24% |
| 5+ children | 40% | 34% | 26% |
Step 3: Apply Income Cap (if applicable)
Texas caps net resources at $11,700/month ($140,400 annually) for 2026. The percentage only applies to income up to this cap. Above-cap support requires proving the child's needs exceed the capped amount.
Melson Formula: Step-by-Step
The Melson Formula (used by Delaware, Hawaii, and Montana) adds a layer of complexity by first ensuring each parent can meet their own basic needs.
Step 1: Calculate Available Income
Start with each parent's net income, then subtract a self-support allowance (a minimum amount needed for the parent's own basic living expenses, typically pegged to the federal poverty level).
Step 2: Determine the Child's Primary Support Need
Use the state's basic needs schedule to determine the minimum cost of raising the child (food, clothing, shelter basics).
Step 3: Allocate Primary Support
Each parent pays their proportional share of the primary support need based on their available income.
Step 4: Apply the Standard of Living Adjustment (SOLA)
A percentage of remaining income above the self-support allowance is added to ensure the child benefits from the parents' higher standard of living. This is what distinguishes the Melson Formula from basic income shares.
Which Model Does Your State Use?
Click any state name to use that state's specific calculator.
Factors That Affect Child Support
Beyond the basic calculation, several factors can increase or decrease the child support amount:
1. Income
Both parents' incomes are the primary driver. Higher combined income = higher obligation. Courts broadly define income to include wages, self-employment, investments, pensions, and benefits.
2. Custody and Parenting Time
The amount of time each parent spends with the children significantly affects the calculation. More parenting time for the non-custodial parent generally reduces the obligation. Many states have a shared custody threshold (often 90-128 overnights) that triggers a different formula. See our 50/50 custody guide.
3. Health Insurance
The cost of health insurance for the children is added to the basic obligation and divided between parents. The parent who provides coverage through their employer plan may receive a credit.
4. Childcare Costs
Work-related childcare expenses (daycare, after-school care) are added to the basic obligation and divided proportionally. Summer camp and before/after school programs typically qualify.
5. Extraordinary Expenses
Special needs, private school tuition, travel costs for visitation, and extraordinary medical expenses not covered by insurance can all affect the final amount.
6. Other Children
If the obligor supports children from other relationships, most states reduce the obligation. Texas uses a multi-family adjustment table. Income Shares states allow deductions for prior child support orders.
7. Standard of Living
Courts may consider the standard of living the child would have enjoyed if the parents remained together, especially in high-income cases where the basic schedule runs out.
Worked Examples by Model
Example 1: Income Shares (Ohio)
Parent 1 (Non-Custodial)
Gross: $5,000/mo. Deductions: $1,250. Adjusted: $3,750.
Parent 2 (Custodial)
Gross: $3,000/mo. Deductions: $750. Adjusted: $2,250.
Combined adjusted: $6,000. Parent 1's share: 62.5%. Schedule lookup for $6,000 / 2 children: $1,088. Parent 1 pays: $1,088 x 62.5% = $680/month.
Example 2: Percentage of Income (Texas)
Obligor's gross income: $6,000/month. Deductions (taxes, FICA): $1,500. Net resources: $4,500. Number of children: 2. Guideline percentage: 25%. Child support: $4,500 x 25% = $1,125/month.
Example 3: High-Income (Texas above cap)
Obligor's net resources: $15,000/month (above $11,700 cap). 1 child at 20%: $11,700 x 20% = $2,340/month. Additional support above the cap requires proving the child's needs.
Frequently Asked Questions
The amount depends on your state's formula, both parents' incomes, the number of children, and custody arrangement. The national average is approximately $430/month for one child and $650/month for two children. Use our state-specific calculators for an accurate estimate.
For one child, most states use the Income Shares model: combine both parents' incomes, look up the basic obligation on a state schedule, then divide proportionally. In percentage-of-income states like Texas, it is typically 20% of net income.
Income Shares (41 states, considers both incomes), Percentage of Income (6 states, flat % of obligor's income), and Melson Formula (3 states, adds self-support allowance before calculating).
The national average is approximately $650/month for two children. In Texas, the guideline is 25% of net resources. In income shares states, the amount depends on both parents' combined income. Use our calculators for your state.
Yes. If either parent's income changes substantially (typically 10-20%), either parent can request a modification. Some states cap income (Texas: $11,700/mo net resources cap).
Most states include wages, salaries, bonuses, commissions, self-employment, rental income, investment income, pensions, Social Security, unemployment, and workers' compensation. Common deductions: taxes, FICA, mandatory retirement, union dues, and prior support obligations.
Key factors: both parents' incomes, number of children, custody/visitation schedule, health insurance costs, childcare expenses, extraordinary medical expenses, other children supported, and the standard of living during the marriage.
Parents can agree on amounts, but most states require the agreement to meet or exceed guidelines. Courts reject agreements significantly below the guidelines without documented reasons. The court always retains jurisdiction to modify in the child's best interest.