Calculating Child Support Under California Guidelines

If you're a parent in California who's getting divorced—or you were never married to your child's other parent—you'll need to deal with pressing questions around child support: Will you receive support for your kids or will you have to pay? How much will the payments be? When can they change or end?

Like all states, California has guidelines to give parents and judges a consistent way to decide on the appropriate amount of child support. The rules in the guidelines—and the formula for calculating support—are very complicated. California provides an online calculator and other resources to help (more on that below). But before you can use those tools, it's important to understand how the guidelines work and when you might qualify for exceptions to the rules.

Who Pays Child Support in California?

Under California law, both parents—whether they're married or not—have an equal, mutual responsibility to support their children according to their ability. When the parents are separated or divorced, one usually pays child support. Meanwhile, the law assumes that the other parent meets their share of the overall support obligation by contributing "a significant portion of available resources" to pay directly for the child's daily needs. (Cal. Fam. Code §§ 3900, 4053 (2024).)

The question of which parent pays child support depends on how much each parent earns and how much time the children spend with each parent (as discussed in detail below). In a traditional situation where one parent has primary physical custody (and earns less than the other parent), the noncustodial parent usually pays child support. But it's common in contemporary divorced families for both parents to spend significant time with their kids.

In California, the parent who earns more typically pays child support—but not always. In some cases, the details of the parents' custody arrangements and the gap between their incomes can lead to a different result. For example, if Parent A has the children more than half the time and earns slightly more than Parent B, the child support calculation might result in a negative number—such as -$150. In that case, Parent B (the low earner) would have to pay $150 a month to Parent A, unless Parent B can justify a different amount (more below on deviations from the guideline). (Cal. Fam. Code § 4055(b)(5) (2024).)

When a child is living with someone other than a parent (such as a legal guardian), both parents may be ordered to pay support for the child.

How Child Support Is Calculated in California

California's child support guidelines include a formula that the state's courts and agencies use to calculate the amount of child support in divorces (known as "dissolution of marriage" in California), support cases involving unmarried parents, and requests to modify existing support orders.

Most parents won't need to do the math when they use the state's online program to estimate their payments (more on that below). But it helps to understand what goes into the formula—and how the details of the parents' circumstances can affect the results.

California's Formula for Calculating Child Support

California's child support formula is complicated, but the basic principle is relatively 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.

Here's the formula: CS = K (HN – (H%)(TN)).

• CS is the child support amount for one child (different multipliers are applied to that amount to come up with the total for more than one child).
• K is the amount of the parents' combined total income that must be devoted to child support (more on that below).

• HN is the higher-earning parent's net monthly disposable income.
• H% is the approximate percentage of time 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% is 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.

The "K value" is calculated under another formula that takes into account the parents' net disposable income and how much time the higher-earning parent spends with the child, applying stepped-up multipliers at various income levels. As part of the changes to California's guidelines that were effective as of September 2024, those income levels and multipliers were changed (for the first time since 1992) to better reflect current economic realities.

(Cal. Fam. Code § 4055 (2024).)

How to Use California's Child Support Calculator

You can use California's official online child support calculator to estimate the amount of support you'll pay or receive. But you should know that a judge could order a different amount 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 calculation. That way, you can be prepared to use the official calculator. And if you believe a different amount of support would be more appropriate, you'll have the context to back up your argument.

Before using the calculator, you'll need to gather information about:

• each parent's gross income, as well as the deductions used to come up with net disposable income
• the percentage of time each child will spend with each parent under their child custody orders, and
• certain other necessary costs for your children.

What Counts as Income When Calculating Child Support?

You'll start by adding up each parent's monthly gross income, which includes:

• wages, salaries, self-employment income, commissions, bonuses, and severance pay
• business income (gross receipts minus operating expenses) and income from rental properties
• pensions and annuities
• investment income, such as interest and dividends
• certain benefits, including workers' compensation, disability, Social Security, unemployment insurance, and veterans' benefits that aren't based on need
• military allowances for housing and food
• 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.

Because California's child support calculation is based on net disposable income, you'll also need to gather information on the expenses that will be subtracted from gross income to come up with that figure. Those expenses include:

• 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
• necessary job-related expenses (which the judge may or may not allow)
• child 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
• necessary expenses related to "extreme financial hardship," which the judge may allow for reasons like a parent's extraordinary health expenses or uninsured catastrophic losses.

(Cal. Fam. Code §§ 4058, 4059, 4070, 4071 (2024).)

Adjustments for Low-Income Parents

California's guidelines presume that parents with a net disposable income below a certain level will qualify for a low-income adjustment to the child support calculation, unless the other parent can prove that the adjusted amount would be unjust or inappropriate under the particular circumstances.

In late 2024, the state raised the threshold for this low-income adjustment, which was previously linked to federal poverty guidelines. Now, parents may qualify when their net disposable income is less than the gross income from a full-time job at California's current minimum wage. As of 2025, the general minimum wage is $16.50 an hour, which works out to $2,860 a month. But that amount is adjusted every year to reflect inflation. (Cal. Fam. Code § 4055(b)(7) (2024).

Don't forget the difference here between gross and net income: Even if you earn more than the minimum wage, you may qualify for the low-income adjustment if your net income is below that amount. When you check the box for the low-income adjustment on the official child support calculator, the program will apply the adjustment.

When a Parent's Earning Capacity Is Used to Calculate Child Support

If a parent's income isn't known (for instance, if that parent didn't submit the required financial declarations when filing for divorce), child support will be calculated based on the parent's earning capacity (often called "imputed income"). Judges may use imputed income in other cases, such as when parents have voluntarily lowered their income to avoid their support duty. (Cal. Fam. Code § 4058 (2024).)

(Learn more about imputing income for child support in California, including the specific circumstances judges consider when determining earning capacity in any case.)

How Parenting Time Affects Child Support

Before you use California's child support calculator, you'll need to know the approximate percentage of time (over the year) that each parent will have "primary physical responsibility" for each child. (Cal. Fam. Code § 4055(b) (2024).)

As California courts have explained, primary physical responsibility may include more than the time when a child is actually with each parent. That means judges might give each parent credit for some of the time their children are in school, depending on who's responsible for getting the child to and from school, responding to emergencies, and other factors. (DaSilva v. DaSilva, 119 Cal.App.4th 1030 (Cal. Ct. App. 2004).)

If you're still negotiating the details of your parenting plan, you could run California's guideline calculator more than once, using different percentages of time with Parent 1. That way, you can see how different custody arrangements would affect the estimated amount of child support.

Expenses Added to Child Support

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:

• childcare expenses that are related to a parent's employment or to education or training that's reasonably necessary to gain employment skills (unless those costs were specifically included in the guideline calculation), 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 (2024).)

These expenses will generally be allocated between the parents in proportion to their respective net incomes (after making allowed adjustments to income, including for spousal support payments), unless a judge finds they should be divided in another way. (Cal. Fam. Code § 4061 (2024).)

Can Child Support 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 allows for higher or lower amounts in some situations.

Allowed Reasons for Deviating from the Child Support Guideline

If you want to argue for an amount of child support that's different than the standard calculation, you'll need to present evidence to convince a judge that it would be "unjust or inappropriate" to use the guideline amount because of the 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
• the paying parent qualifies for the low-income adjustment, and the guideline amount is more than 50% of that parent's net disposable income after application of the adjustment
• 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 (2024).)

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 (2024).)

Can Parents Agree on a Child Support Amount?

Parents may—and usually do—agree with each other about the amount of child support, either as part of an overall divorce settlement agreement or just on the support issue. To do that in your case, you'll still need to start 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 guidelines.

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 (2024).)

Thanks to the guidelines, 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 (as discussed above).

If you and your spouse are having trouble working out agreements on these issues, you may turn to mediation for help. Be aware that if you haven't agreed on a parenting plan by the time you file for divorce, the court will require you to participate in custody mediation. When that happens, you can get free mediation through the court—but it will deal with custody only, not child support.

How to Apply for Child Support

If you're seeking child support when your marriage is ending, you'll simply include 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.

Outside of the divorce context, you may apply for child support by enrolling for services from California's Department of Child Support Services (DCSS). If needed, the agency may also help you establish the child's legal parentage.

How to Collect Child Support

Child support is usually paid through income withholding. That way, employers take the money out of the pay of the parents who owe support. The payments are then forwarded to the recipient parents, generally through a direct deposit to their bank accounts or an electronic payment card.

When income withholding isn't possible (such as when parents are self-employed), judges may order parents to deposit up to a year's worth of child support payments to guarantee payment.

Parents may get help enforcing child support in California from the DCSS and the state's courts.

How to Modify Child Support in California

Judges may order a change (called a "modification") in child support when 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) (2024).)

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, or
• one parent has been incarcerated.

The fact that one or both parents married again won't, by itself, justify a child support modification. But certain changed financial circumstances as a result of remarriage might affect child support in California, including the need to support children from the new relationship.

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 review 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.

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 (2024).)

Other Resources and Help With Child Support

In addition to the services available from the California DCSS and local child support agencies (described above), the Family Law Facilitator in your county can provide information and assistance with child support, including help with:

• calculating support
• filling out the necessary forms, and
• requests to modify child support.

Despite all of these resources, you may need a lawyer's help in some circumstances, such as when you and your co-parent can't agree on a request for a modification or an amount of child support that's higher or lower than the standard guideline calculation. Also, if you haven't been able to agree on a parenting plan, even after mediation, an experienced family law attorney can help you sort out the connected issues of custody and child support.