How to Calculate Child Support Payments in California

Learn how to calculate child support in California, when the amount of support may differ from what’s calculated under the state’s guidelines, and how to apply for, collect, and modify child support.

By , Attorney · UC Law San Francisco

California has child support guidelines that parents and courts use to calculate the appropriate amount of support that one parent will pay when the parents are divorced, are legally separated, or were never married and aren't living together. Parents can use these guidelines when negotiating a child support agreement (more on that below). And if they can't agree, a judge will use the guidelines to craft a child support order.

How to Use the California Child Support Calculator

To estimate the amount of child support that may be ordered in your case, you can use the state's official Child Support Guideline Calculator. The guidelines are largely based on both parents' incomes and their custody arrangements, as well as certain child-related expenses.

Learn more about calculating child support under California guidelines, including what gets counted as income when calculating support.

Figure Out Your Custody Schedule

Before you start with the calculator, you'll need to know the percentage of time your children will spend with each parent throughout the year. (If you haven't worked out a parenting plan yet, you could try the calculator with different percentages to see how different custody arrangements would affect the amount of support.)

Gather the Information You Need for Child Support Calculator

To enter the correct information into the Calculator, you'll need to gather the following financial information and documents:

  • both parents' recent tax returns
  • both parents' paycheck stubs
  • both parents' W2s or 1099s
  • records of certain benefits (like workers' compensation, social security, disability, or unemployment)
  • proof of mandatory payroll deductions (like union dues, retirement, or state disability insurance)
  • documentation of child support and spousal support from other relationships
  • the cost of health insurance for the parents and children
  • the cost of the children's uninsured medical costs
  • job-related child care expenses
  • travel expenses for visitation, and
  • expenses related to the child's educational or special needs such as private school tuition and sports registration fees.

Keep in mind that not all of the boxes in the calculator will apply to your case. Also, you and your child's other parent might have to negotiate about some of the information you'll enter, such as which parent gets to claim the child as a dependent on tax returns.

The Guideline Formula

California uses a mathematical formula to calculate child support. The formula is expressed as CS = K[HN - (H%)(TN)].

Don't worry, you don't have to solve the equation yourself (the calculator takes care of that for you), but it's helpful to understand the components of the formula:

  • CS is the child support amount for one child.
  • K is the amount of both parents' income to be allocated for child support.
  • HN stands for the higher-earning parent's net monthly disposable income.
  • H% is the percentage of time the higher-earner has or will have primary physical responsibility for the child compared to the other parent.
  • TN is the total net monthly disposable income of both parents.

If you have multiple children, you don't just multiply the child support amount (CS) by the number of children you have. The guideline provides specific multipliers to use. For example, if you have 2 children, you multiply CS by 1.6, and so on.

(Cal. Fam. Code §§ 3900-4076 (2024).)

When Child Support May Be Different Than the Guideline Amount

California law presumes that the amount of child support calculated by the guideline formula is the right amount of support. Still, it allows judges to order a different amount of support in some situations. (Cal. Fam. Code §§ 4056, 4057 (2024).)

Parents Can Agree to a Different Amount of Child Support

Parents can—and often do—agree on an amount of child support as part of a divorce settlement. Sometimes they agree to the guideline amount and sometimes they negotiate for a different amount.

If you want to deviate from the guideline, you'll need to calculate the guideline amount first and then declare that the amount you've agreed on instead is:

  • in your children's best interests
  • will adequately meet their needs, and
  • using the guideline amount would be unjust or inappropriate in your situation.

Whether you're agreeing to the guideline or a different amount, you'll need to file a Stipulation to Establish or Modify a Child Support Order (Form FL-350) for a judge to review and approve. Both parents must sign the stipulation.

(Cal. Fam. Code §§ 3585, 4065 (2024).)

A Judge Can Decide That the Guideline Amount Is Unjust or Inappropriate

If parents can't agree on an amount, a judge will decide for them. Judges typically order the guideline amount but they can deviate when the guideline amount would be unjust or inappropriate.

Examples of situations when California law would allow deviation include:

  • the parent paying support has an extraordinarily high income and the guideline amount would exceed the needs of the children (like Kevin Costner)
  • the parents have different time-sharing arrangements for different children, or
  • the children have special medical or other needs that could require more support.

(Cal. Fam. Code §§ 4057 (2024).)

How to Apply for Child Support in California

You may apply for child support as part of the process of filing for divorce in California. You'll share financial information with your spouse and try to work out a child support agreement. If you can't reach an agreement, you can go to trial and have a judge decide.

If you aren't married to your child's other parent, you can get help with requesting support by enrolling in California Child Support Services. If needed, child support services can also help you establish parentage and locate an absent parent.

How to Collect Child Support in California

When a judge orders support, the parent who is ordered to pay typically signs an Income Withholding for Support Order (Form FL-195). The form tells the parent's employer to take the support payment directly from the parent's paycheck. You can agree to put an Income Withholding Order on hold if you trust the other parent to pay you directly.

If you're not receiving support payments, the local child support agency (LCSA) can help you collect unpaid support and interest. The agency has many ways to help collect support, including:

  • taking income tax refunds, workers' compensation, or unemployment benefits
  • reporting the debt to credit bureaus
  • seizing money from a bank account
  • putting a lien on property (like a house), and
  • suspending the parent's driver's or professional licenses.

How to Change a Child Support Order

At any time, either parent may ask to change a child support order (called a "modification"). You might ask a judge for a modification if circumstances have changed since your last order, such as:

  • you've lost your job or your income has decreased
  • the other parent's income has increased
  • you're spending more time with your child, or
  • your family size changes.

You can ask the local child support agency to review your current child support order to see if a modification is needed at no charge. Modifications are typically granted if the support order would change by 20% or $50, whichever is less.

If you and the other parent agree on a change, you can submit a Stipulation to Establish or Modify Child Support and Order (Form FL-350) for a judge to review and approve. If you can't agree, you can file a Request for Order (Form FL-300) and ask a judge to change the order.

The sooner you make the request the better. A judge can only change the support amount from the date you filed your request, not the date your circumstances changed.

(Cal. Fam. Code §§ 3651, 3653 (2024).)

Getting Help With Child Support

Calculating child support is complicated and often emotionally fraught. The Judicial Branch of California publishes a self-help guide to child support with step-by-step instructions on preparing a child support agreement and requesting a child support order.

But you don't have to figure it out on your own. Free help is available in every county in California at the family law facilitator's office. And, as previously noted, you can also get assistance from the local child support agency, especially if you need to establish your child's paternity, locate the other parent, or enforce an existing child support order.

There are some situations when you may need a lawyer's help, especially when you and your co-parent can't agree about child support, custody, or both. It can be complicated to predict how different parenting agreements—and even what you'll do with the family home after divorce—will affect child support and your ability to meet your children's (and your own) needs. An experienced family law attorney can explain your options and their consequences, negotiate a fair agreement for you, and represent you in court if it comes to that.

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