Child Support Calculator

The Income Shares Model rests on one premise: a child should not be worse off financially because the parents live apart. To approximate that, both parents' incomes are combined, a basic support obligation for that combined income and number of children is read from a published schedule, and the obligation is then divided in proportion to what each parent contributes to the combined income.

The practical consequence is that the number that matters is the ratio between the two incomes, not either income on its own. Two households at very different income levels produce the same order if the split between the parents is the same.

A parent who has the child for a large share of overnights is already paying part of the child's day-to-day cost directly, so a guideline that ignored overnights would charge that cost twice. Most states therefore apply a shared-care or shared-physical-custody adjustment.

Forty percent of overnights is a common trigger, but the shape of the credit differs by state: some use a simple percentage reduction, some treat the shared time as a separate household with its own costs, and some leave it to judicial discretion. The credit applies to the basic obligation rather than acting as a dollar-for-dollar offset, which is why an even split does not normally reduce support to zero.

A guideline figure is a starting point, not an order. Courts routinely deviate for a child's special needs, a parent's extraordinary travel to preserve the relationship, or a self-support reserve that would otherwise leave a parent below subsistence.

This calculator applies one simplified national schedule rather than any single state's table, so it deliberately returns the same number whichever state you select. Use it to understand how the inputs interact, then confirm the figure with your state child-support agency or a family-law attorney before relying on it.