Calculating Child Support Under California Guidelines

Learn how child support works in California, including how support is calculated, reasons for departing from the guideline, support agreements, and modifying support amounts.

By , Legal Editor

If you're splitting up with your child's (or children's) other parent (or you were never a couple), among your most pressing questions will be whether you'll pay or receive support for your child—and, if so, how much the child support will be. Like all states, California has a uniform guideline for calculating child support. But unlike some other states, California's guideline isn't based just on the parents' incomes. It's a complicated formula that also takes into account how much time each parent spends with the child.

Whether parents agree on support or a judge has to decide for them, the rules in the state's guideline will still apply. So it's important to understand the basics of how child support works in California, including how to get help collecting support and how to change the amount of support you're already paying or receiving.

What Is the California Child Support Calculator?

California provides an online child support calculator that you can use to estimate the amount of support that might apply in your case. But you should know that a judge could very well order a different amount of support in your case, after taking into account various factors allowed under California law.

We'll discuss those factors below, as well as explain the numbers that go into the child support calculator. That way, you can be better prepared when gathering all the information you'll need to use the calculator. And if you believe a different amount of support would be more appropriate, you'll have the context to back up your argument.

Applying California's Child Support Guideline

As you'll see below, California's formula for calculating child support is very complicated. However, the basic outline is fairly straightforward: As a general rule, the greater the difference between the parents' incomes and the less time the higher-earning parent spends with the children, the more child support that parent will owe.

The formula is used whenever child support needs to be calculated as part of a court case, including:

  • divorces (known as "dissolution of marriage" in California)
  • support cases involving unmarried parents
  • dissolution of domestic partnerships, and
  • requests to modify existing support orders.

Gathering the Information for the Child Support Calculation

Before you can calculate the amount of child support, you must gather certain information:

Gross income includes:

  • wages, salaries, self-employment income, commissions, and bonuses
  • business income (gross receipts minus operating expenses) and income from rental properties
  • pensions
  • investment income, such as dividends, interest, and annuities
  • certain benefits, including workers' compensation, disability, social security, and unemployment insurance
  • spousal support received from a previous marriage to another person (but not child support received for children from a different relationship), and
  • if the judge decides it's appropriate, employee benefits that reduce living expenses.

In some cases, California judges may "impute" income to parents who've intentionally lowered their actual income to avoid their duty to support their children, by considering their "earning capacity" along with their actual income. (Cal. Fam. Code § 4058 (2022).)

To figure net disposable income, you'll subtract a number of items from gross income, including:

  • actual state and federal income taxes (not necessarily the withholding amount), as well as taxes for Social Security and Medicare
  • mandatory payroll deductions for union dues, retirement, or state disability insurance
  • health insurance premiums for the parent and children
  • child support or spousal support (alimony) payments for someone who's not a part of the current case (such as for children from a previous relationship or an ex from a previous marriage), and
  • a deduction for "extreme financial hardship," when a judge finds that it's necessary for reasons like a parent's extraordinary health expenses.

(Cal. Fam. Code §§ 4059, 4060, 4070, 4071 (2022).)

The guideline presumes that parents with primary physical custody will directly contribute a significant part of their resources to supporting their children. (Cal. Fam. Code Cal. Fam. Code § 4053, 4058, 4059, 4070, 4071 (2022).)

The Guideline Formula

The formula California uses to calculate child support is: CS = K (HN - (H%)(TN)).

Here's what the letters mean:

  • CS is the child support amount. This is what the formula will calculate once you've plugged in all of your information. The amount will be for one child. (See below for how to multiply that number when you have two or more children.)
  • K is the amount of the parents' combined total income that must be devoted to child support. That amount is calculated under another formula that takes into account how much the parents earn and on how much time the higher-earning parent spends with the child, applying stepped-up percentages as income levels go up.
  • HN stands for high net—the higher-earning parent's net monthly disposable income.
  • H% is the approximate percentage of time that the high earner has or will have primary physical responsibility for the children compared to the other parent. When parents have different time-sharing arrangements for different children, H% equals the average of the approximate percentages of time the high earner parent spends with each child.
  • TN is the combined total net monthly disposable income of both parents.

(Cal. Fam. Code § 4055 (2022).)

How California's Guideline Applies to More Than One Child

After calculating the guideline amount for one child, you won't simply multiply the result by the number of children covered by the support order. Instead, the guideline provides specific multipliers, such as:

  • for two children: multiply the support amount (CS in the formula) by 1.6
  • for three children: multiply by 2
  • for four children: multiply by 2.3, and
  • for five children: multiply by 2.5.

The law provides multipliers for up to 10 kids. These multipliers sometimes change, but the state's online calculator should include the current numbers. (Cal. Fam. Code § 4055(b)(4) (2022).)

When a Parent Who Earns Less Must Pay Child Support

Traditionally, mothers had physical custody of their children after divorce, while fathers earned more and paid child support. The gender pay gap persists, but it's much more common in contemporary divorced families for both parents to spend significant time with their kids.

Higher-earning parents are still typically the ones who pay child support. However, the formula in California's guideline sometimes results in a negative amount of child support. When that happens, the lower-earning parent generally pays that amount to the high earner. (Cal. Fam. Code § 4055(b)(5) (2022).)

For example, say there isn't a big difference between the parents' earnings, and the higher-earning parent has the children more than half of the time. If the formula results in −$200 for the amount of child support, the low earner would have to pay $200 a month to the high earner—unless the low earner can justify a different result based on the legal reasons for departing from the guideline (discussed below).

Child Support Add-Ons Under the California Guideline

In addition to the basic guideline support amount, parents might be required to contribute to certain expenses for the children's benefit. Some of these add-ons are mandatory, while others are discretionary (meaning they're up to the judge).

As additional child support, judges must order parents to pay:

  • any child care costs that are needed because of a parent's job or education (as long as the education or training is reasonably necessary to gain employment skills), and
  • reasonable uninsured health care expenses for the child.

When it's appropriate, judges may order parents to pay additional support for:

  • expenses related to a child's special needs, including educational needs, and
  • travel expenses for visitation.

(Cal. Fam. Code § 4062 (2022).)

When a judge orders child support add-ons, the parents will generally contribute an equal amount for those additional expenses. However, a judge may order the parents to contribute unequal amounts when a parent provides documentation showing that the different apportionment would be more appropriate under the circumstances. For example, if one parent makes far less than the other, a judge may order the high earner to pay more than half of the child care costs that are needed for both of them to work outside the home.

If an unequal allocation is warranted, the judge will first calculate the standard guideline amount and then apportion the add-ons between the parents in proportion to their net disposable incomes—after making allowed adjustments to income, including for spousal support payments. (Cal. Fam. Code § 4061 (2022).

When Child Support May Be Different Than the Guideline Amount

California law presumes that the amount of child support calculated under the guideline formula will be proper in any individual case, but it does allow for departures from the guideline amount in some situations.

Allowed Reasons for Deviating from the Child Support Guideline

If you want to argue for a different amount of support, you'll need to present evidence to convince a judge that application of the guideline would be "unjust or inappropriate" because of the special circumstances in your case, including:

  • you and the other parent have agreed on a different amount of support and have met the legal requirements for that agreement (discussed below)
  • the parent being ordered to pay child support has an extraordinarily high income and the guideline amount would be more than the children need
  • one parent isn't contributing to the children's needs at a level that matches that parent's custodial time
  • both parents have roughly equal time with the children, but one parent has to pay a much lower or higher percentage of income for housing than the other parent
  • you've deferred the sale of the family home after divorce, and the rental value is more than the mortgage payments, property taxes, and insurance
  • you will have different time-sharing arrangements for different children
  • your children have special medical or other needs that require more support, or
  • your children have more than two legal parents (which is allowed under California law).

(Cal. Fam. Code § 4057 (2022).)

Guideline Departures Must Follow California's Child Support Policies

In addition to proving that applying the guideline would be inappropriate for one of the reasons listed in the law, you'll also need to demonstrate that the departure from the guideline would be consistent with the basic child support principles in California law, including the following:

  • The children's interests are the top priority under the guideline, and they should share both of their parents' standard of living. That means it could be appropriate if child support payments improve the living standard in the entire household where the children live most of the time.
  • Child support orders must ensure that the amount of support is enough to reflect the high costs of raising a family in California and the state's relatively high standard of living, compared to other states.
  • When both parents have a significant amount of time with their children, the amount of support should also reflect the increased costs of raising kids in two homes, and it should minimize any differences between the living standards in those homes.

(Cal. Fam. Code §§ 4053, 4057 (2022).)

Requirements for Child Support Agreements

Parents may—and usually do—agree with each other about the amount of child support, either as part of an overall marital settlement agreement or just on the support issue. To do that in your case, you can start out by using the state's calculator to estimate the guideline amount of support. Then, if you want to negotiate for any adjustments to that amount, you could apply the rules (discussed above) for deviating from the guideline.

Be aware, however, that you will need to submit your agreement (or "stipulation") to the court for approval. If the agreed amount of support is below the guideline amount, the judge won't approve it unless you and the other parent(s) declare that:

  • the agreed amount of support will be in the children's best interests and be enough to meet their needs
  • you know and understand your rights when it comes to child support
  • you weren't forced or coerced into signing the agreement, and
  • neither parent is receiving or has applied for public assistance.

(Cal. Fam. Code § 4065 (2022).)

Thanks to the guideline, it's usually easier to reach an agreement on the amount of child support than other issues in divorce. But negotiations about support often get tangled up with decisions about the exact amount of timeshare—because that will affect the child support calculations. If you and your spouse are having trouble working out agreements on these issues, you may turn to mediation for help.

How Long Does Child Support Last in California?

Generally, the legal obligation to pay child support lasts until the child turns 18. There are exceptions to that cut-off, including:

  • If an 18-year-old is still a full-time high school student, the support duty continues until age 19.
  • Parents may agree to pay some form of child support beyond age 18 or high school graduation. For instance, some parents agree to contribute to their children's college educations.
  • Parents are legally obligated to provide as much support as they can for their adult children who are incapacitated to such an extent that they can't earn a living, and who don't have other sufficient means of support.

(Cal. Fam. Code §§ 3901, 3910 (2022).)

How to Apply for or Collect Child Support

If you're seeking child support when your marriage is ending, you'll simply make the request in the petition and other paperwork when you file for divorce in California. You can also apply for temporary child support while your case is proceeding.

When you aren't married to your child's other parent, you may apply for child support services from the California Child Support Services Agency. If needed, the agency may also help you establish the child's legal parentage. It may also provide assistance with collecting and enforcing child support in California.

How to Request a Change in Child Support

Once a child support order is in place, it's not necessarily set in stone. Judges may order a change (called a "modification") in child support whenever they believe it's necessary. If the existing order was based on both parents' agreement for a below-guideline amount of support, one parent may request an increase in support at any time, without showing that their situation has changed. (Cal. Fam. Code §§ 3651, 4065(d) (2022).)

In all other situations, however, California courts have consistently held that anyone requesting a modification must show that there has been a significant change in circumstances that requires a different amount of support. Usually, judges will grant a modification when the changed circumstances would justify an increase or decrease of 20% or $50 per month, whichever is less.

Some common reasons for modifying support include when:

  • a parent has involuntarily lost a job or income
  • a parent is making more money than before
  • there's been a change in the amount of time each parent is caring for the child or children
  • a parent needs to support a new child with a different partner, or
  • one parent has been incarcerated.

Keep in mind that when one parent requests a child support modification, the judge must consider both parents' current financial situations and time-share with the child. That could lead to unexpected results—for instance, when the primary custodial parent has also seen an income reduction.

Your local child support agency will provide a review of your case (for free) to see if a modification is justified. Even if the agency denies your request, you may still ask a judge to modify the support order. Your local Family Law Facilitator or a family law attorney can help with your request.

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