California Child Support Calculator

How California Calculates Child Support

California determines child support using the Algebraic Formula (Guideline Calculator), the standard set out in Cal. Fam. Code § 4055. California applies a statewide algebraic formula that weighs both parents' net incomes alongside the amount of time the child spends with each parent, so parenting time directly affects the result.

The calculator above applies that formula to the income and expense figures you enter and shows each step of the math, so you can see exactly how the estimate is built. Because every order ultimately runs through a judge, the guideline figure is a starting point rather than a guaranteed result — the sections below explain what goes into it and where real orders can differ.

Key Rules Behind the California Formula

• California uses an algebraic formula: CS = K × [HN − (H% × TN)], where K accounts for income level and custody time.
• SB 343 (effective September 1, 2024) updated the K factor income brackets for the first time since 1992 and changed how add-on expenses are divided.
• K is computed from total net income (TN) brackets and the higher earner's custody percentage (H%).
• For multiple children, the one-child support amount is multiplied by a statutory factor (e.g., 1.6× for 2 children, 2.0× for 3).
• A low-income adjustment applies when the obligor earns less than full-time minimum wage ($2,860/month in 2025).
• California courts can deviate from the guideline amount in extraordinary circumstances, but the formula amount is presumptively correct.

What Counts as Income

Child support guidelines are built on each parent's income, so the figure you enter matters more than any other input. Most states start from a broad definition of gross income that includes wages, salary, tips, commissions, bonuses, self-employment earnings, and many forms of government benefits, then subtract specific deductions to reach the income the formula actually uses.

California's rules under Cal. Fam. Code § 4055 spell out which deductions apply and whether the formula runs on gross or net income. The calculator's field labels tell you which figure to enter; when in doubt, use your most recent pay stubs and tax return, and confirm the details in the California child support laws guide.

How to Establish a Child Support Order in California

A child support obligation becomes enforceable only once a court or the state child support agency issues an order. Either parent can request one, and in California, as in every state, the local child support agency that operates under the federal Title IV-D program can open a case, locate the other parent, establish paternity if needed, and ask the court to set support using the guideline formula.

When you apply, expect to provide proof of income for both parents, the child's information, and details about health insurance and childcare costs — the same inputs this calculator uses. Running your numbers here first gives you a realistic idea of the order amount before you file.

How to Modify a California Child Support Order

Child support orders are not permanent. California courts can revisit an order when there has been a substantial change in circumstances — for example, a significant change in either parent's income, a change in custody or parenting time, or a meaningful change in the child's needs. Federal rules also entitle parents in IV-D cases to request a review periodically (often about every three years) even without a major change.

To estimate a new amount, re-run the calculator with the updated figures. If the guideline result is meaningfully different from your current order, that gap is often what supports a modification request — though only a court can actually change the order.

How Child Support Is Enforced in California

Once an order is in place, California has strong tools to collect it. The most common is income withholding: federal law requires most new orders to be paid through automatic wage garnishment, so payments are deducted from the paying parent's paycheck. When payments fall behind, enforcement can escalate to intercepting tax refunds, suspending driver's or professional licenses, placing liens on property, reporting the debt to credit bureaus, and, in serious cases, contempt-of-court proceedings.

Interest and penalties can accrue on unpaid support, so an order that goes unaddressed tends to grow rather than disappear. If your circumstances have changed, seeking a modification through the court is almost always better than simply paying less than the order requires.

Disclaimer

This calculator provides estimates only and is not a substitute for legal advice. The actual amount ordered by a California court may differ based on factors including but not limited to: the special needs of the child, travel expenses for visitation, extraordinary educational or medical expenses, the parents' other support obligations, and the court's discretion to deviate from the guidelines. For advice about your specific situation, consult a licensed California family law attorney.

← Read the full California child support laws guide