How Child Support Is Calculated

Child support amounts can seem arbitrary to parents seeing a number for the first time, but nearly every state uses a defined formula rather than a judge's unguided discretion.

The Two Main Calculation Models

The income shares model, used by most states, calculates support based on the combined income of both parents and the amount they would have spent on the child if the household were still together, then divides that responsibility proportionally.

The percentage of income model, used by a smaller number of states, calculates support as a set percentage of the paying parent's income, adjusted for the number of children.

Factors That Adjust the Base Calculation

Most state formulas account for the amount of parenting time each parent has, since more overnight time with a parent generally reduces that parent's support obligation, and additional expenses like health insurance, childcare, and extraordinary medical or educational costs.

Courts can deviate from the standard formula in unusual circumstances, such as a child with special needs or a parent with significantly fluctuating income.

Where the Formula Might Not Apply Cleanly

Self-employed parents, parents with irregular income, and high-income parents whose earnings exceed the formula's built-in guidelines often require additional analysis beyond the basic calculation.

Imputed income — where a court calculates support based on what a parent could be earning rather than what they claim to earn — can apply in cases involving suspected underemployment.

Frequently Asked Questions

Can child support be modified later?

Yes, generally when there's been a significant change in either parent's income or the custody arrangement.

Does child support cover college expenses?

It depends on the state; some extend support obligations to cover certain college costs, while others end the standard obligation at 18 or high school graduation.

Child support calculations involve more variables than most parents expect. An attorney can help ensure the calculation accurately reflects your income, expenses, and parenting arrangement.