California Child Support: The Guideline Formula
California sets child support with a statewide uniform guideline formula (Fam. Code § 4055) based on both parents' incomes and timeshare. A major reform (SB 343) became operative September 1, 2024, changing how income is allocated and the low-income adjustment. Use the official Judicial Council calculator and confirm the current statute.
By Find Local Law Editorial Team · Last reviewed: May 26, 2026
Researched and drafted with AI assistance and verified against primary sources (statutes, Judicial Council forms, and official court websites). This is general information, not legal advice.
This is general information, not legal advice. Talk to a California attorney about how these rules apply to your situation.
California sets child support with a statewide formula, not a judge’s gut feeling — but the rules changed significantly in 2024, so current numbers matter.
The guideline formula
California uses a statewide uniform guideline formula (Fam. Code § 4055). It runs on both parents’ incomes and the timeshare — the percentage of time each parent spends with the child. Courts use an approved guideline calculator, so the amount is meant to be consistent across the state rather than left to each judge.
Important: the 2024 reform
A major guideline reform, SB 343, became operative September 1, 2024 — the first big revision in decades. It changed how income is allocated between the parents and revised the low-income adjustment. Because of this, you should not rely on older articles or rules of thumb. Use the current official Judicial Council calculator and confirm the current statute — the rules changed as of September 1, 2024.
Estimate before you rely
You can run an estimate with the official guideline support calculator. Treat the result as a starting point: the exact outcome depends on how the current rules treat your income, deductions, and timeshare.
How it connects
Support is usually decided alongside child custody, because timeshare feeds the formula. If the parents weren’t married, parentage generally has to be established first.
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Start your free intakeFrequently asked questions
- How is child support calculated in California?
- California uses a statewide uniform guideline formula (Fam. Code § 4055) that runs on both parents' incomes and the percentage of time each spends with the child. Courts use an approved guideline calculator, so the result is meant to be consistent statewide.
- Did California's child support rules change recently?
- Yes. A major guideline reform (SB 343) became operative September 1, 2024 — the first big revision in decades — changing the income-allocation and the low-income adjustment. Because the rules changed, use the current official calculator and confirm the current statute before relying on older figures.
- Where can I estimate my support amount?
- Use the official Judicial Council guideline calculator at selfhelp.courts.ca.gov/support-calculator. It reflects the current rules; an attorney can confirm how your specific income and timeshare apply.
Sources
Related guides
- California Child Custody: Legal vs. Physical & Best Interest California splits custody into legal (decision-making) and physical (where the child lives), each of which can be joint or sole. Courts decide by the child's best interest, weighing § 3011 factors like health, safety, and abuse history. The court cannot prefer a parent based on sex, gender, or sexual orientation.
- California Divorce: No-Fault Grounds, Residency & Timeline California is a pure no-fault state. Almost every divorce rests on 'irreconcilable differences' (Fam. Code § 2310). You must be a California resident six months and a county resident three months before filing (§ 2320), and a divorce can't be final until at least six months after the respondent is served or appears (§ 2339).
- California Domestic Violence Restraining Orders (DVRO) California's Domestic Violence Prevention Act (Fam. Code § 6200 et seq.) lets people in covered relationships seek a restraining order. 'Abuse' is broader than physical injury (§ 6203), and a DVRO can order no-contact, stay-away, move-out, and address custody, support, and firearm restrictions.
- California Parentage: Establishing Legal Parents California's Uniform Parentage Act (Fam. Code § 7600 et seq.) governs establishing the legal parent-child relationship. A Voluntary Declaration of Parentage (§ 7570 et seq.) signed by both parents has the force of a judgment. Parentage is the legal predicate for custody, visitation, and child support.
- California Property Division: Community Property California is a community property state. Property acquired during the marriage (Fam. Code § 760) is generally divided equally — 50/50 — absent a written agreement (§ 2550). Separate property owned before marriage or received by gift or inheritance (§ 770) isn't divided. This differs from equitable-distribution states.
- California Spousal Support: Factors & the 10-Year Rule California has temporary support during a case and long-term support at judgment. Long-term support is set by the Fam. Code § 4320 factors, not a formula. Under § 4336, a marriage of 10+ years is presumed 'of long duration' so the court retains jurisdiction indefinitely — but that's not an automatic right to lifetime support.