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Custodial timeshare calculator

California guideline support is driven by two things: each parent's net income and the timeshare percentage — the share of the year each child spends with each parent. This works out that percentage precisely from your schedule.

Why this page does not output a dollar figure

The California guideline formula uses a statutory coefficient that varies with combined net income and the higher earner's share of it. Reproducing that table from memory and getting a bracket wrong would produce a number that looks authoritative and is wrong — in a context where people make real decisions. So this tool computes the input courts argue about most, and points you at the state's own calculator for the dollar amount.

Your parenting schedule

of 14

Overnights are the usual unit. Count where the child actually sleeps, not who is nominally “on”.

days

Net extra days beyond the regular rotation — summer blocks, alternating holidays, spring break.

hrs

Midweek dinners, school pickups, activities. Courts vary on whether these count — shown separately below.

children

Timeshare

32.6% / 67.4% Parent A / Parent B, overnights only

Based on 4 of every 14 overnights plus 14 extra days a year.

  • Regular overnights per year 104
  • Extra days per year 14
  • Parent A total days 118
  • Parent B total days 247
  • Parent A timeshare 32.3%

Counting the additional non-overnight hours as well would put Parent A at 0%. Whether these count is frequently disputed — raise it explicitly rather than assuming.

What the guideline formula actually uses

California child support is formulaic rather than discretionary — the court starts from a statewide guideline calculation and departs from it only in defined circumstances. The formula takes:

InputWhat it meansHow much it moves the number
Each parent's net disposable incomeGross income less taxes, mandatory retirement, union dues, health premiums and certain other deductionsVery high
Timeshare percentageThe share of time the higher earner has primary physical responsibilityVery high
Number of childrenApplied as a multiplier to the base figureHigh
Tax filing statusFiling status and dependant claims change net incomeModerate
Health insurance & childcareAdded on as separate contributionsModerate
Hardship deductionse.g. other children living in the homeCase-specific

Why timeshare is the number people fight over

Because it is the one input a parent can change by negotiation rather than by earning differently. Moving from four overnights a fortnight to five is a 7-percentage-point swing in timeshare, and near the middle of the range the support figure responds sharply to it.

That is also why courts are alert to schedules proposed for financial rather than parenting reasons — and why an agreed schedule that nobody actually follows tends to unravel at the first review.

Count what happens, not what the order says

If the order says alternate weekends but one parent has in practice had the children four nights a week for a year, the practical timeshare is not what the paperwork says. Keep a simple calendar record — it is the single most useful document in a modification request.

Getting the official figure

The State of California publishes a guideline calculator, and LA County's Department of Child Support Services can also run the calculation. Family law attorneys and mediators use licensed software that applies the same formula with fuller tax handling.

Take three things with you: this timeshare percentage, recent pay records for both parents, and the current cost of health insurance and childcare for the children.

Common questions

Does 50/50 custody mean no child support?
No. Equal timeshare reduces support but does not eliminate it where incomes differ. The formula is designed so that a child's standard of living does not swing sharply between two households, which requires a transfer whenever earnings are unequal.
Can we just agree an amount between ourselves?
Parents can agree an amount, but a court must be satisfied it is in the child's interests before making it an order, and an agreement below guideline gets closer scrutiny. An informal arrangement with no order is also unenforceable if it breaks down — which it frequently does.
What if the other parent is hiding income?
Courts can impute income where a parent is deliberately unemployed or under-employed, or where reported income is inconsistent with lifestyle. This requires evidence rather than suspicion, and it is a common reason to involve an attorney rather than proceeding alone.
How often can support be changed?
When there is a material change of circumstances — a job loss, a significant income change, or a genuine change in the parenting schedule. Support is not automatically recalculated; someone has to ask.
Not legal advice. This tool performs date arithmetic on a schedule you describe. It does not calculate guideline support and should not be presented as doing so. Use the state's guideline calculator or a family law attorney for the dollar figure.