California Child Support Calculator
The statewide guideline formula from Family Code 4055, using both parents' net income and how much time each spends with the children.
California child support follows one formula statewide: CS = K[HN − (H%)(TN)]. The parent with more income and less time with the children usually pays. Enter each parent's monthly income and the custody time share to estimate the guideline amount.
Use net income if you know it (after taxes, health insurance and mandatory retirement). Otherwise, estimate it from gross pay.
Child Support Calculator
Estimated Guideline Child Support
Parent A net
Parent B net
Combined net (TN)
K factor
How this is calculated
The formula is CS = K[HN − (H%)(TN)] (Family Code 4055):
- HN is the higher earner's net monthly disposable income.
- TN is both parents' net monthly disposable income added together.
- H% is the share of time the higher earner has primary physical responsibility for the children.
- K is (1 + H%) when H% is 50% or less, or (2 − H%) when it is more, multiplied by a fraction that depends on TN.
If the result is positive, the higher earner pays it. If it is negative, the lower earner pays the absolute value. The TN fractions set in the law (as amended effective September 1, 2024):
| Combined net income (TN) per month | Fraction used in K |
|---|---|
| $0–$2,900 | 0.165 + TN ÷ 82,857 |
| $2,901–$5,000 | 0.131 + TN ÷ 42,149 |
| $5,001–$10,000 | 0.25 |
| $10,001–$15,000 | 0.1 + 1,499 ÷ TN |
| Over $15,000 | 0.12 + 1,200 ÷ TN |
For more than one child, the one-child amount is multiplied by the factor in the law (for example 1.6 for two children and 2 for three). The order assigns the one-child amount to the youngest child and the difference between tiers to each older child.
Low-income adjustment. If the paying parent's net income is below full-time state minimum wage (currently about $2,929 a month), the law presumes the court should lower the amount. The reduction can be up to the amount × (that monthly figure − the payer's net income) ÷ that monthly figure. The calculator shows that maximum. The court decides the actual reduction.
Estimating net income from gross pay. In gross-pay mode the calculator subtracts California and federal income tax (single filer, standard deduction), Social Security and Medicare, and SDI, then the deductions you enter. Real cases use each parent's actual filing status and deductions, which can change the result by hundreds of dollars.
Not included: mandatory add-ons for child care and uninsured health costs (Family Code 4062), hardship deductions for other children, and imputed income. The court can add these to the guideline amount.
Frequently Asked Questions
How is child support calculated in California?
California uses a statewide guideline formula in Family Code 4055: CS = K[HN - (H%)(TN)]. HN is the higher earner's net monthly disposable income, TN is both parents' combined net income, H% is the higher earner's share of custodial time, and K is a fraction set by the law that depends on combined income and the time share. The result is multiplied for more than one child.
Does 50/50 custody mean no child support in California?
Not necessarily. With equal time, the parent who earns more still usually pays support, because the formula compares each parent's income, not just the schedule. Support is zero at 50/50 only when both parents have about the same net income.
What income counts for California child support?
The formula uses net disposable income: income from almost any source (wages, self-employment, bonuses, rental income and more) minus income taxes, FICA, mandatory retirement contributions, health insurance for the parent and children, other child or spousal support actually paid, and certain job-related expenses (Family Code 4058 and 4059).
Can a California child support order be changed later?
Yes. Either parent can ask the court to modify support when circumstances change, such as a job loss, a big raise or a new custody schedule. The new amount is recalculated with the same guideline formula, generally from the date the request is filed.
Is this the same number the court will order?
It uses the same statutory formula, but courts run certified software with each parent's actual tax filing status, deductions and add-ons such as child care and uninsured medical costs. Treat this as an estimate. The court can also deviate from guideline in limited situations (Family Code 4057).
This tool provides an educational estimate only and is not legal advice. Courts calculate support with certified software using each parent's full financial information, add mandatory child care and medical costs, and may deviate from guideline. Talk to a family law attorney or your local child support agency (DCSS) about your case.