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How Child Support Is Calculated: Statutory Models and Income Guidelines

Sarah J. Sterling, Esq.
Reviewed by Sarah J. Sterling, Esq.
Senior Legal Editor & Consumer Rights Attorney (J.D., Member of the State Bar) • Fact-checked: Mar 26, 2025
Educational Purpose: This guide provides general legal information and is not formal legal advice. Laws vary by state and individual facts. If you face an active legal dispute, consider speaking directly with a licensed attorney.

Every state uses statutory child support guidelines to ensure children receive adequate financial support based on parental economic capability. Federal law mandates that states review and maintain uniform calculation formulas.

Primary State Child Support Models

  • Income Shares Model (Used in 41 States): Calculates what total parental income would have been spent on the child if the parents lived together, then divides that support amount proportionally based on each parent's percentage of total income.
  • Percentage of Income Model: Applies a flat percentage of the non-custodial parent's gross or net income depending on the number of children (e.g., 20% for one child, 25% for two).
  • Melson Formula: A comprehensive model that ensures each parent's basic self-support needs are met before calculating child support and standard-of-living adjustments.

Key Variables Impacting Monthly Obligations

Calculations incorporate gross incomes, overnight parenting time ratios, health insurance premium contributions, mandatory childcare expenses, and preexisting support orders for other children.

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