Two Main Calculation Models
Income Shares Model (used by ~40 states including CA, TX, FL, NY)
Combines both parents' incomes and assigns each parent a proportional share of the total child-rearing cost. The non-custodial parent pays their share to the custodial parent.
Percentage of Income Model (used by ~10 states including WI, MN, ND)
Non-custodial parent pays a fixed percentage of their income regardless of the custodial parent's income. Example: 17% for 1 child, 25% for 2, 29% for 3 (varies by state).
Factors That Affect the Calculation
- Both parents' gross monthly income
- Number of children
- Custody split (overnight percentage)
- Health insurance costs paid by each parent
- Childcare costs
- Other children either parent supports
- Extraordinary expenses (medical, educational)
Rough Estimates by Income
| Non-Custodial Income | 1 Child (est.) | 2 Children (est.) |
|---|---|---|
| $3,000/mo | $450–650 | $650–900 |
| $5,000/mo | $750–1,100 | $1,100–1,600 |
| $8,000/mo | $1,200–1,800 | $1,700–2,500 |
Estimates only. Actual amounts set by court using state guidelines.
Frequently Asked Questions
How is child support calculated in most states?
Most states use the Income Shares Model: both parents' incomes are combined, the state tables determine total child-rearing cost, and each parent contributes proportionally. Custody percentage further adjusts the amount.
Does 50/50 custody eliminate child support?
Not always. Even with equal custody, if there's a significant income disparity, the higher-earning parent may still owe support. The exact calculation depends on your state's formula.
Can child support be modified?
Yes — either parent can request a modification if there's been a substantial change in circumstances (income change of 15%+, custody change, new job, disability). Courts review based on current guidelines.
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