A formula, not a negotiation
California applies a statewide guideline calculation. Courts start from the guideline figure and depart from it only in defined circumstances, which is why arguments about support are really arguments about the inputs.
The two inputs that move it most are net disposable income and timeshare — and timeshare is the one parents can change by agreement, which is why it is contested so often.
What counts as income
Broadly, income from all sources: salary, self-employment, commissions, bonuses, rental income, and in some circumstances perquisites that reduce living expenses. Net disposable income is that figure less taxes, mandatory retirement contributions, union dues, health premiums and certain other deductions.
Where a parent is deliberately unemployed or under-employed, a court can impute income — but this requires evidence rather than suspicion.
Add-ons
Childcare needed for work or training, and uninsured medical costs, are typically shared in addition to the base figure. Extracurricular activities and private education may be, depending on circumstances and the family's history.
Get the timeshare number right first
It is arithmetic, it is contestable, and it moves the figure sharply. Our timeshare calculator computes it exactly from your schedule — take that number to any consultation.