How California calculates child support
- California uses one formula for every case: CS = K[HN − (H%)(TN)], where HN is the higher earner’s net disposable monthly income, TN is both parents’ combined net disposable income and H% is the higher earner’s share of time with the children.
- K is a fraction set by a table in Family Code section 4055 (from 0.165 + TN/82,857 for combined net income up to $2,900, to 0.25 for $5,001–$10,000, falling above $10,000), multiplied by 1 plus H% when the higher earner has the children half the time or less, or by 2 minus H% when more.
- The one-child result is multiplied by 1.6 for two children, 2 for three, 2.3 for four, 2.5 for five, and up to 2.86 for ten.
- A positive result is paid by the higher earner; a negative result is paid by the lower earner.
- When the paying parent’s net income is below $2,929 a month (full-time state minimum wage, $16.90 an hour from January 1, 2026), the law presumes a low-income adjustment; the lowest amount of the adjustment range is presumed correct unless rebutted.
- Net disposable income is gross income minus actual state and federal income tax, Social Security and Medicare, mandatory retirement and union dues, health insurance premiums, support paid for other children and other items in Family Code section 4059. This calculator starts from net income; the official calculator computes it from gross income.
What the calculator asks
- How many children is the support for?
- What percentage of the time are the children in your care?
- Your net disposable income per month
- The other parent’s net disposable income per month
It never asks for names, Social Security numbers or account numbers, and your answers are not saved.
What the estimate leaves out
- Working out net disposable income from gross income (income taxes and the other Family Code section 4059 deductions): enter each parent’s net figure
- Child care and uninsured health care costs the court adds to guideline support (Family Code section 4062)
- Hardship deductions for other children in the home, unless already subtracted from the net income you enter
- Deviations the court may make from the guideline (Family Code section 4057)
- Spousal support and its effect on income
When a situation is outside what the calculator covers, it says so and points you to the official worksheet instead of guessing.
Official sources
- Family Code § 4055, statewide uniform guideline (operative September 1, 2024)
- Family Code § 4059, net disposable income
- Judicial Council: guideline support calculators and the 2026 low-income adjustment threshold ($2,929)
- Judicial Council: low-income adjustment thresholds 1994–2026
- Judicial Council: Review of the Statewide Uniform Child Support Guideline 2025
- California Child Support Guideline Calculator (Department of Child Support Services)
California Child Support Guideline Calculator (DCSS) →
Ready to estimate? The calculator shows each worksheet line so you can check it against the official form.
Open the California calculator →An estimate from the published guideline formula, not a prediction of a court order. The official court worksheet and the court’s decision control. General information, not legal advice. LawCat is not a law firm.