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.
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.
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 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)).
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).)
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:
You'll start by adding up each parent's monthly gross income, which includes:
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:
(Cal. Fam. Code §§ 4058, 4059, 4070, 4071 (2024).)
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.
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.)
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.
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:
When it's appropriate, judges may order parents to pay additional support for:
(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).)
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.
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:
(Cal. Fam. Code § 4057 (2024).)
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:
(Cal. Fam. Code §§ 4053, 4057 (2024).)
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:
(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.
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.
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.
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:
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.
Generally, the legal obligation to pay child support lasts until the child turns 18. There are exceptions to that cut-off, including:
(Cal. Fam. Code §§ 3901, 3910 (2024).)
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:
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.