Data & Methodology
How ChildSupport.app calculates child support estimates across all 50 US states and the District of Columbia.
Calculation Models
The United States uses three primary models for calculating child support obligations. Each state has adopted one of these models, sometimes with significant state-specific modifications.
Income Shares Model (41 States)
The Income Shares model is based on the principle that children should receive the same proportion of parental income they would have received if the parents lived together. Both parents' incomes are combined to look up a base obligation in a state-specific schedule table. Each parent is then responsible for their proportional share based on their percentage of combined income. Adjustments are made for healthcare, childcare, and custody time.
Percentage of Income Model (6 States)
Used by Texas, Wisconsin, North Dakota, Mississippi, Alaska, and Nevada. This model applies a fixed percentage to the non-custodial parent's income based on the number of children. For example, Texas applies 20% for one child, 25% for two, and so on. Some states use gross income while others use net. This is the simplest model but doesn't account for the custodial parent's income.
Melson Formula (3 States)
Used by Delaware, Hawaii, and Montana. The Melson Formula is an advanced variation of the Income Shares model. It first ensures each parent can meet their own basic needs through a self-support reserve before allocating child support. It also provides for a standard of living adjustment (SOLA) when income exceeds basic needs, ensuring children benefit from both parents' financial success.
How State Formulas Work
Regardless of model, most state formulas follow a similar general process:
- 1Determine each parent's gross or net monthly income (varies by state)
- 2Apply allowable deductions (taxes, mandatory retirement, existing support orders)
- 3Look up or calculate the base child support obligation
- 4Allocate the obligation between parents based on income shares or apply a flat percentage
- 5Add extraordinary expenses (healthcare premiums, childcare, special needs)
- 6Apply custody time adjustments for shared parenting arrangements
- 7Apply deviation factors where applicable (travel costs, high income, special circumstances)
Data Sources
- •State Statutes & Code: Each state's child support guidelines as codified in state law (e.g., California Family Code §4050-4076, Texas Family Code §154).
- •Court Administrative Guidelines: Rules of Judicial Administration and court orders that establish support schedules (e.g., Alabama Rule 32, Pennsylvania Rule 1910.16).
- •Official State Calculators: We cross-reference our estimates against state-provided calculators where available to ensure accuracy.
- •Federal Poverty Guidelines: Published annually by the U.S. Department of Health & Human Services, used for self-support reserve calculations.
- •USDA Expenditures on Children: The foundational research behind Income Shares schedules, based on the Cost of Raising a Child reports.
Limitations
⚠️ This tool provides estimates only and is not a substitute for legal advice or official state calculators.
- •Simplified income bracket tables may not perfectly match official state schedule tables with hundreds of rows.
- •Judicial discretion can result in orders above or below guideline amounts.
- •Complex situations (multiple families, self-employment, imputed income) require professional guidance.
- •State guidelines are periodically updated; our data may have a lag of up to a few months after legislative changes.
- •Tax calculations are simplified and may not reflect individual tax situations precisely.
Update Frequency
We review and update state guidelines on an ongoing basis. Most states update their guidelines every 2-4 years. When a state publishes new schedules or amends its formula, we incorporate changes typically within 30-60 days.
Our last comprehensive review was completed in February 2026. Each state page shows its individual last-updated date.
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