Child Support Payment Calculator
Estimate monthly child support payments using both parents' incomes, custody split, number of children, and shared childcare costs. Designed for parents preparing for divorce or custody negotiations.
About this calculator
Child support is typically calculated by applying an income-based percentage to the paying parent's (payor's) gross income, then adjusting for custody time and shared expenses. The formula used here is: Support = (payorIncome × (0.15 + (numChildren − 1) × 0.05)) − (custodyPercentage / 100 × payorIncome × 0.1) + (childcareExpenses × payorIncome / (payorIncome + payeeIncome)). The first term sets a base obligation — 15% of the payor's income for one child, rising 5% per additional child. The second term reduces support proportionally when the payor has custody time, reflecting direct spending on the child. The third term splits childcare expenses between parents based on their income ratio. This model approximates the income shares approach used by many U.S. states, though actual court orders depend on state-specific guidelines, tax considerations, and judicial discretion.
How to use
Example: Payor income = $5,000/month; payee income = $3,000/month; 2 children; payor custody = 30%; childcare = $400/month. Step 1: Base obligation — $5,000 × (0.15 + 1 × 0.05) = $5,000 × 0.20 = $1,000. Step 2: Custody credit — (30/100) × $5,000 × 0.10 = $150. Step 3: Childcare share — $400 × ($5,000 / $8,000) = $250. Step 4: Total — $1,000 − $150 + $250 = $1,100/month estimated child support.
Frequently asked questions
How does custody percentage affect the monthly child support amount?
Greater parenting time by the paying parent reduces their child support obligation because they are directly spending on the child's needs during their custody period. In this calculator, each percentage point of custody reduces the base obligation by 0.1% of the payor's income. Many states apply a similar parenting-time credit, though the exact reduction formula varies. Some states only apply a custody credit once the payor's share exceeds a threshold, such as 20% or 35% of overnights, to prevent token visitation from inflating credits.
What expenses are included in child support and what must be paid separately?
Basic child support covers food, housing, clothing, and general daily living costs for the child. Childcare expenses, health insurance premiums, and extraordinary medical costs are frequently handled as add-ons split between parents in proportion to income. Educational expenses, extracurricular activities, and college costs may or may not be included depending on your state and the specific divorce agreement. It is important to distinguish between what the court order mandates and what parents voluntarily agree to, as only court-ordered amounts are enforceable through wage garnishment or contempt proceedings.
How do I modify child support if my income changes significantly after the order is issued?
To modify a child support order, you generally must show a substantial change in circumstances — typically defined as an income change of 10–20% or more, depending on the state. You file a motion to modify with the court that issued the original order and provide documentation such as pay stubs, tax returns, or proof of job loss. Courts do not retroactively reduce support, so arrears that accrued before the modification filing date remain owed. Many states allow administrative reviews every three years without proving a change in circumstances, which is a simpler route if you qualify.