Child support calculations vary by state, but most use one of three models:
Income Shares Model (used by most states): Both parents' incomes are combined to determine the total support obligation based on the number of children. The obligation is then divided proportionally based on each parent's share of combined income. The custody schedule also affects the calculation.
Percentage of Income Model: The non-custodial parent pays a percentage of their income based on the number of children. For example, 17% for one child, 25% for two children, etc.
Melson Formula: Used in Delaware, Hawaii, and Montana. Similar to Income Shares but includes a self-support reserve to ensure the paying parent retains enough income for basic needs.
Factors considered: Both parents' gross income, number of children, custody arrangement, healthcare costs, childcare expenses, other support obligations, and special needs of the child.
Modifications: Child support orders can be modified if there is a significant change in circumstances — job loss, substantial income change, change in custody arrangement, or change in the child's needs.
Duration: Child support typically continues until the child turns 18 (or 19-21 in some states), graduates from high school, becomes emancipated, or enters active military service.