Pro Se Guide

How Child Support Is Calculated

Child support is calculated using state-specific formulas based primarily on parents' incomes and the custody arrangement. Most states use either the "Income Shares" model (both parents' incomes combined) or "Percentage of Income" model (non-custodial parent's income only). The amount typically covers basic needs like housing, food, clothing, healthcare, and education expenses.

Last updated: February 2026 • Reviewed by Divorce.law Legal Team

The Three Child Support Models

Income Shares Model (41 States)

Combines both parents' incomes to determine total support obligation, then divides it proportionally based on each parent's share of combined income.

Example Calculation:

  • • Parent A earns $60,000/year (60% of combined)
  • • Parent B earns $40,000/year (40% of combined)
  • • Combined income: $100,000
  • • Guideline support for 2 children: $18,000/year
  • • Parent A pays: $10,800/year ($900/month)

Percentage of Income Model (6 States)

Applies a flat percentage of the non-custodial parent's income. Simpler but doesn't account for custodial parent's income.

Typical Percentages:

  • • 1 child: 17-20% of gross income
  • • 2 children: 25-28% of gross income
  • • 3 children: 29-32% of gross income
  • • 4+ children: 31-35% of gross income

Melson Formula (3 States: DE, HI, MT)

A more complex version of income shares that first ensures each parent's basic needs are met before calculating support.

Key Features:

  • • Protects parents' self-support reserve
  • • Ensures children's primary needs met first
  • • Shares additional income after basics covered
  • • Most protective of low-income parents

Factors That Affect Child Support

May Increase Support

  • Higher income of paying parent
  • More children to support
  • Child's special medical or educational needs
  • Childcare costs for working parent
  • Health insurance premiums for child

May Decrease Support

  • More parenting time with paying parent
  • Lower income of paying parent
  • Other children to support
  • Higher income of receiving parent
  • Child has independent income

What Counts as "Income"?

Child support calculations use "gross income" from all sources, not just wages. Courts look at the full financial picture.

Included as Income

  • • Wages and salary
  • • Bonuses and commissions
  • • Self-employment income
  • • Rental income
  • • Investment dividends and interest
  • • Retirement/pension income
  • • Social Security benefits
  • • Unemployment benefits
  • • Workers' compensation
  • • Trust income

Usually Not Included

  • • Public assistance (TANF, SNAP)
  • • SSI (Supplemental Security Income)
  • • Child support received for other children
  • • Foster care payments
  • • Income of new spouse (usually)
  • • Gifts and inheritances (varies by state)
  • • Student loans

Imputed Income Warning

If a parent is voluntarily unemployed or underemployed, courts may "impute" income—calculating support based on what they could earn, not what they actually earn.

Modifying Child Support

Child support orders can be modified when circumstances substantially change. Either parent can request a modification.

Common Reasons for Modification

  • Significant income change (increase or decrease)
  • Job loss or new employment
  • Change in custody arrangement
  • Child's needs have changed
  • Cost of living adjustment
  • New child from another relationship

Tip: Most states require a change of 15-20% or more before they'll modify support. You cannot modify support retroactively—changes apply from the filing date forward.

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