US-CaliforniaHow is child support calculated in California?
Child support in California is calculated using the state's mandatory guideline formula, which considers both parents' incomes, tax filing status, time each parent spends with the child, and certain deductions.
What the Law Says
California uses a statutory guideline formula to determine child support, designed to ensure consistent, fair, and predictable orders. The law presumes that the guideline amount is correct unless special circumstances justify deviation.
The calculation is based on the 'income shares' model, meaning both parents’ combined net disposable income is used to estimate the total amount both would have spent on the child if they lived together. That amount is then divided between the parents proportionally to their respective incomes.
Key inputs include gross income (wages, bonuses, rental income, etc.), mandatory deductions (taxes, union dues, health insurance), and the percentage of time each parent has primary physical responsibility for the child (often called 'timeshare').
The court may also order 'add-ons' — such as health insurance premiums, uninsured medical expenses, and reasonable childcare costs — which are typically split between parents in proportion to their incomes.
Statutory TextThe court shall apply the child support guidelines… and shall issue a child support order in that amount, unless the court makes a written finding or a finding on the record that the application of the child support guidelines would be unjust or inappropriate.
— Family Code § 4052 — Presumption that guideline is correct
Statutory Text‘Net disposable income’ means the income of the parent remaining after the deduction of all required deductions… including, but not limited to, federal and state income taxes… health insurance premiums… and mandatory union dues.
— Family Code § 4058 — Definition of net disposable income
Statutory TextThe court may order either or both parents to pay an amount for the support of the child that is necessary for the child’s health insurance coverage… and for the child’s uninsured medical expenses.
— Family Code § 4062 — Add-on expenses
What Courts Have Said
California appellate courts have consistently upheld the presumption in favor of guideline support and clarified how courts must apply discretion when deviating from it.
The court held that a deviation from the guideline requires specific factual findings showing why the guideline amount would be unjust or inappropriate—vague or conclusory statements are insufficient.
Confirmed that voluntary unemployment or underemployment may result in imputation of income, and that courts must consider earning capacity—not just actual income—when calculating support.
What to Do
Gather complete income documentation (pay stubs, tax returns, proof of other income) for both parents.
Calculate timeshare accurately (e.g., using overnight count or percentage of time) — even small changes affect support significantly.
Use the official California Guideline Calculator (available at www.courts.ca.gov/selfhelp-childsupport) or consult a family law facilitator.
Disclose all mandatory deductions and potential add-on expenses (health insurance, childcare, education).
If requesting deviation from the guideline, prepare detailed written findings explaining why the guideline amount would be unjust or inappropriate.
Sources
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South KoreaNot legal advice. This article is general information based on publicly available sources, written for educational purposes. Laws change and individual situations vary. Consult a licensed attorney in your jurisdiction before acting on anything you read here. Last reviewed: 2026-06-08.