In California, child support is based on a complex calculation that takes into consideration the parents’ incomes, how much time each parent spends with the child, and any tax deductions that are available to either parent. This formula is applied whenever the support of a minor child is to be determined, including in dissolutions (divorces), paternity, and domestic partnership cases. The Statewide Child Support Guideline can be found at California Family Code Section 4050. Below, we explain how California's child support guidelines work. For more information on the divorce process in California, see our California Divorce and Family Law page. For more articles on child support, check out our Child Support area.

Purposes of the Guideline

There are two purposes for the guideline: to provide for a minimum level of child support for a child; and to provide for uniformity in the calculation of child support. To achieve these purposes, state law requires judges to follow the guideline, with deviations allowed only in limited and specified situations.

Underlying Principles

The guideline statute begins by setting forth the principles that courts are to follow in applying the rules. Among those principles are the following:

• A parent’s first and principal obligation is to support his or her minor children according to the parent’s situation and station in life.
• Both parents are mutually responsible to support their children.
• The guideline is presumed to be correct in all cases, and only under special circumstances should child support orders fall below the child support mandated by the guideline formula.
• Child support orders must ensure that children actually receive fair, timely, and sufficient support, which reflects the state’s high standard of living and high costs of raising children compared to other states.

Applying the Guideline

The guideline itself is a very complex algebraic formula that uses the parents' income, deductions, and time spent with the child to come up with a dollar amount for child support. Like other states, California has an online child support calculator you can use to come up with the applicable amount in your case. To determine child support, you must have:

• the gross incomes of each parent
• the percentage of time each child spends with each parent
• any available income tax deductions that the parents can claim, such as mortgage interest
• mandatory payroll deductions, such as health insurance, pensions, and union dues, and
• child care costs incurred by either parent.

Once you plug this basic information into the calculator, it will generate an amount.

The Formula

Just in case you didn't believe it was complicated, here is the formula California uses to calculate child support:

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. If a couple has more children, they must multiply the CS amount by a figure set out in the law, which depends on the number of children.
• K is the combined total of both parents' income to be allocated for child support. (The amount of the parents' combined income that must be devoted to child support, in turn, depends on how much the parents earn and on how much time the higher-earning parent spends with the child.)
• HN stands for high net: The net monthly disposable income of the parent who earns more.
• 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. (For example, that parent might have the children 25% of the time, while the other parent has them 75% of the time.) In cases in which 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.

Now you can see why everyone -- including lawyers and judges -- uses a calculator! Generally speaking, though, the greater the disparity between the two parents' income and the less time the higher earning parent spends with the children, the more child support that parent will owe.

Deviations from the Guideline Amount

California Family Code §4057(a) states that the guideline amount of child support, as determined by the formula, is “presumed to be the correct amount of child support to be ordered.” This means that the judge is required to order the guideline level of child support, unless there is a good reason why a different amount of child support would be appropriate.

In creating the child support guideline, the California legislature understood that there may be situations when the mechanical application of the guideline would not be fair or reasonable. Family Code §4057(b) contains a list of factors which, if present, can justify a judge’s decision to award child support that is higher or lower than the amount generated by the guideline formula. Among those factors are:

• The parent being ordered to pay child support has an extraordinarily high income and the amount determined under the formula would exceed the needs of the children.
• A parent is not contributing to the needs of the children at a level commensurate with that parent’s custodial time.
• Both parents have substantially equal time with the children and one parent has a much lower or higher percentage of income used for housing than the other parent.
• The children have special medical or other needs that could require child support greater than the formula amount.

Child Support Add-Ons

In addition to the basic child support guideline amount, a parent can be ordered to contribute to specified expenses that are for the benefit of the children. Family Code §4062 lists two types of child support add-ons:

• Mandatory add-ons: The judge is required to order a contribution to the following as additional child support: (1) child care costs related to employment or to reasonably necessary education or training for employment skills; and (2) the reasonable uninsured health care costs for the children.
• Discretionary add-ons: The judge can also order a parent to contribute to: (1) costs related to the educational or other special needs of the children; and (2) travel expenses for visitation (this appears to refer only to travel expenses incurred by the custodial parent).

If the judge orders any child support add-ons, such expenses are to be equally shared by the parents. However, where an equal allocation of these expenses is not reasonable, the court is authorized to allocate them between the parents in proportion to their net spendable incomes. Family Code §4061(b) provides that the following three-step procedure is to be followed to determine the parents’ respective net spendable incomes for purposes of allocating the child support add-ons:

• First, the guideline child support amount is to be calculated.
• Second, the amount of guideline child support is to be deducted from the income of the paying parent but not added to the income of the receiving parent.
• Third, if one parent is paying spousal support to the other parent, the amount of spousal support is to be deducted from the income of the paying parent and added to the income of the receiving parent.