Family Law & Divorce · Haute Lawyer Network
How Is Child Support Calculated?
Last reviewed: May 2026
Child support is calculated according to each state's guidelines — formulas established by state law that determine the appropriate amount of support based primarily on both parents' incomes and the custody arrangement.
The Two Primary Models
Income Shares Model — used by the majority of states — calculates support based on the combined income of both parents and apportions the obligation proportionally. The theory is that the child should receive the same proportion of parental income they would have received if the family had stayed together.
Percentage of Income Model — used by fewer states — bases support on a fixed percentage of the non-custodial parent's income, regardless of the custodial parent's earnings.
Key Factors in the Calculation
Both parents' gross incomes — including wages, salaries, bonuses, commissions, rental income, and investment income. Courts can also impute income to a parent who is voluntarily unemployed or underemployed.
The custody arrangement — the more time a parent spends with the child, the more direct costs they bear. Most states reduce child support obligations when the non-custodial parent has 40% or more of overnights.
Healthcare costs — the cost of health insurance and unreimbursed medical expenses is factored into the calculation.
Childcare costs — work-related childcare expenses are generally included.
Other children — existing child support obligations for children from a prior relationship may reduce available income.
Can Child Support Deviate from the Guidelines
Yes. State guidelines create a presumptive amount that courts start with. Judges can deviate when circumstances warrant — the child's special needs, a parent's very high income, or equal time sharing by both parents — but must state reasons in writing.
Can Child Support Be Modified
Yes. Either parent can petition for modification when there has been a substantial change in circumstances — a significant change in either parent's income, a change in the custody arrangement, or a change in the child's needs.
Frequently Asked Questions
How is child support calculated if parents share custody equally?
When parents have approximately equal custody, most states still use the income shares model but offset the amounts each parent would theoretically owe. The parent with higher income typically pays support to the other, but the amount is reduced to reflect equal time sharing.
Does child support cover college expenses?
In most states child support ends at age 18 or high school graduation. A few states allow courts to order post-secondary educational support. Parties can also agree to contribute to college expenses in their settlement agreement.
Can a parent refuse visitation if child support is not paid?
No. Child support and visitation are legally separate. A parent cannot withhold visitation because the other parent is not paying support. The remedy for non-payment is a motion for enforcement — not denying access to the child.
What happens if a parent hides income to avoid child support?
Courts can discover hidden income through financial discovery and subpoenas. If a parent is found hiding income, courts can impute income based on earning capacity and impose sanctions.
How long does child support last?
In most states child support continues until the child turns 18 or graduates from high school, whichever is later. Support continues indefinitely for a child with a disability who cannot become self-supporting.
Related Questions
Are you a Family Law & Divorce attorney?
Join Haute Lawyer Network and have your profile featured alongside these answers.
Apply for Membership →This information is provided for general informational purposes only and does not constitute legal advice or create an attorney-client relationship.