How is child support calculated in California?
California child support is calculated with one statewide formula, Family Code § 4055: it uses both parents’ monthly net disposable income and the higher earner’s share of parenting time, and this calculator runs that formula as re-enacted by SB 343 and operative since September 1, 2024.[1]
CS = K × [HN − (H%) × TN]
- HN is the higher earner’s monthly net disposable income and TN is both parents’ total.
- H% is the share of time the higher earner has primary physical responsibility for the children.
- K is the share of income allocated to child support. It is a K-factor that depends on TN, multiplied by (1 + H%) when the higher earner has the children 50% of the time or less, or by (2 − H%) when they have them more.[1]
A positive result is paid by the higher earner. A negative result means the lower earner pays the amount to the higher earner. For more than one child, the one-child amount is multiplied by 1.6 for two children, 2 for three, 2.3 for four, 2.5 for five and 2.625 for six, up to 2.86 for ten.[1]
The K-factor by total net income
The K-factor is about 0.20 to 0.25 of total net income for most families; it is highest from $5,001 to $10,000 a month and falls slowly above that.[1]
| Total net disposable income (TN) | K-factor | Example TN | K-factor at the example |
|---|---|---|---|
| $0 – $2,900 | 0.165 + TN ÷ 82,857 | $2,000 | 0.1891 |
| $2,901 – $5,000 | 0.131 + TN ÷ 42,149 | $4,000 | 0.2259 |
| $5,001 – $10,000 | 0.25 | $8,000 | 0.2500 |
| $10,001 – $15,000 | 0.10 + 1,499 ÷ TN | $12,000 | 0.2249 |
| Over $15,000 | 0.12 + 1,200 ÷ TN | $20,000 | 0.1800 |
What counts as net disposable income
Net disposable income is gross income from all sources minus the deductions in § 4059: state and federal income tax actually owed, FICA, mandatory union dues and retirement, health insurance premiums, court-ordered support paid for other people, and job-related or hardship deductions the court allows.[3]
California’s own calculator works out the taxes from gross income. This estimator asks for net disposable income directly, because a faithful income-tax computation needs your filing status and deductions. Your pay stub’s take-home pay is a starting point; add back voluntary deductions such as 401(k) contributions, which are not allowed.
Low-income adjustment for 2026
When the paying parent’s net disposable income is below $2,929 a month in 2026, the court presumes a reduction of up to CS × (2,929 − net income) ÷ 2,929.[1][7] The $2,929 threshold equals full-time state minimum wage and changes every January.[6]
The Judicial Council’s 2025 review gives an example: a parent with $2,500 of net income and no timeshare, with one child, has a formula amount of $488, reduced by up to $71 to $417.[8] Our result shows the full reduction and states the range, which the statute requires calculators to display.
Child care and health costs (add-ons)
Child care needed for work or job training and reasonable uninsured health costs are added to basic support, split in proportion to the parents’ net incomes after the paying parent’s income is reduced by the basic support (§ 4061(d)).[4][5] Education and special needs costs, and travel for visitation, are discretionary add-ons. Before September 1, 2024 the default split was 50/50.
When the court can depart from the formula
The formula amount is presumed correct, but § 4057 lets the court order a different amount, with findings, in cases such as these:[2]
- the parents agree to a different amount;
- an extraordinarily high earner’s formula amount exceeds the children’s needs;
- a parent is not contributing in line with their custodial time;
- special circumstances, such as different timeshares for different children or a child’s special needs.
If support after the low-income adjustment would exceed half of the paying parent’s net income, the court may reduce it, but not below that 50% (§ 4057(b)(5)).[2]
How long California support lasts and how to change it
California child support continues past 18 for an unmarried child who is a full-time high school student and not self-supporting, until the child finishes 12th grade or turns 19, whichever comes first.[11]
- Modification. A support order can be modified or ended at any time the court finds necessary, but not for amounts that came due before the request to modify was filed, so file as soon as circumstances change.[12]
- Getting an order. The local child support agency, part of the Department of Child Support Services, can open a case, calculate support with the guideline calculator and enforce the order.[10]
Official California calculator and agency
The Department of Child Support Services publishes the state’s Guideline Calculator, which computes taxes from gross income and is the tool child support agencies use.[9][10]
- California DCSS Guideline Calculator
- California Department of Child Support Services
- Family Code § 4055
For tables of typical amounts by income and parenting time, see how much child support is in California. To see how other states set support, compare the Texas child support calculator (paying parent’s income only) or read how much child support is across states.
An estimate, not an order. Courts compute net income from actual tax figures and decide the amount. Not legal advice; see our legal disclaimer.
Frequently asked questions
How much is child support for 1 kid in California?
It depends on both incomes and timeshare. With net incomes of $6,000 and $4,000 and 20% time with the higher earner, the formula gives $1,200 a month. With no timeshare it gives $1,500.00.
What percentage of income is child support in California?
There is no single percentage. K is roughly 20–25% of combined net income for one child, adjusted for timeshare, and the higher earner pays the part above their own time-weighted share.
Does 50/50 custody mean no child support in California?
No. With equal time, the higher earner still pays when incomes differ. At $6,000 and $4,000 net with 50/50 time, the formula gives $375.00 a month for one child.
Does California child support stop at 18?
Not always. It continues for an unmarried full-time high school student who is not self-supporting, until the child finishes 12th grade or turns 19, whichever is first.
Is this California child support calculator 2026 current?
Yes. It uses the SB 343 formula in force since September 1, 2024 and the 2026 low-income adjustment threshold of $2,929 a month.
Sources
- Family Code § 4055 (statewide uniform guideline formula)
- Family Code § 4057 (presumption and rebuttal factors)
- Family Code § 4059 (net disposable income)
- Family Code § 4061 (allocation of add-on expenses)
- Family Code § 4062 (additional child support: child care, health care)
- Guideline Support Calculators and Low-Income Adjustment threshold
- Low-Income Adjustment threshold by year, 1994–2026
- Review of the Statewide Uniform Child Support Guideline 2025 (report to the Legislature)
- California Guideline Child Support Calculator user guide
- Guideline Calculator
- Family Code § 3901 (support for a high school student age 18)
- Family Code § 3651 (modification or termination of support)