How California Calculates Child Support
California uses the Income Shares model to determine child support obligations. This page explains the guidelines, formula, and key factors.
Model Type
Income Shares (algebraic formula)
California computes support with the statutory algebraic formula CS = K[HN − (H%)(TN)], where K is an income- and time-share-based factor, HN is the higher earner's net income, and TN is the parents' combined net income. The one-child result is then scaled up for additional children.
Sources & Verification
- The § 4055(b)(7) low-income adjustment is not applied.
- Net disposable income is entered directly rather than computed from gross income under §§ 4059-4060, so the result is only as accurate as the user's net figure.
Income Basis & Definitions
net monthly disposable income (both parents)
Determines K factor in the guideline formula.
Source: §4055(b)(3) K factor table by number of childrenNet monthly disposable income as defined by Family Code §4059–§4060 (gross less taxes, mandatory deductions).
Source: §4059 gross income definitionNet monthly disposable income of the other parent.
Source: §4059 gross income definitionParenting Time Handling
Percentage of time each parent has physical custody (H%); directly used in guideline formula CS = K[HN - (H%)(TN)].
Source: §4055(b)(1)(D) approximate time-share percentageDeductions & Adjustments
Hardship deductions for extraordinary health expenses, uninsured catastrophic losses, or other qualifying children per §4071.
Source: §4071 hardship deduction categories