California child support is set by a state-mandated formula. The formula lives in Family Code section 4055 and is run, in practice, through software called XSpouse. This essay walks through how the formula works and what arguments commonly succeed at hearing.
The guideline formula
The starting point is each parent's net disposable income and the percentage of time each parent has primary physical custody. The formula assumes the higher earner pays the lower earner; the percentage of time the higher earner has the children reduces the support they owe.
The presumption is that the guideline number is correct. A court can deviate, but only if the deviation is supported by specific findings.
Common arguments at hearing
- Imputed income: when one parent is voluntarily underemployed, the court can impute income at their earning capacity.
- Special-needs additions: medical, educational, or developmental expenses can be added on top of guideline.
- Hardship deductions: extraordinary financial obligations (other children, large medical debt) can reduce the obligor's calculated income.
The right move depends on the specific facts. If the numbers in your XSpouse calculation don't match what you can actually afford or what the children actually need, that's exactly the kind of issue an attorney can address.
This essay is general information, not legal advice. Every case turns on its specific facts. If you're facing one, talk to an attorney about yours.