Formulas to Determine Child Support in California

by Heather Frances Google

    When a California couple with children divorces, the court determines how much child support the non-custodial parent should pay. Because California’s formula to calculate child support is so complicated, the courts depend on a computer program to calculate the actual amount, but parents are responsible for providing the information required for input into this program.

    Income Shares Model

    California uses the Income Shares model to calculate child support. This model assumes a child should receive the same portion of his parents’ income for support as he would have received if his parents had not divorced. This limits the financial disadvantage to the child that might otherwise occur after a divorce. The Income Shares model is the most commonly used model in the United States.

    Net Income

    California’s statutory formula is based on the net disposable incomes of both parents. To determine the net disposable income of each parent, the court first calculates a parent’s income from all sources to determine the total gross income. Then, it removes all allowable deductions, such as union dues, taxes and health insurance premiums. The remaining income is the net disposable income used to calculate the proper amount of child support.


    California’s Family Code Section 4055 contains the formula for calculating child support. The formula calculates the amount of payment allocated for child support based on both parents’ incomes. The formula also factors in the higher-earning parent’s approximate amount of physical responsibility for the children in addition to both parents’ total monthly net incomes. When a non-custodial parent earns a higher percentage of the combined parental income, the court will likely order that parent to pay child support based on that higher proportion of the combined incomes.


    When there is more than one child in the family, the amount of child support calculated from the formula is multiplied by a certain figure, based on the number of children, to arrive at the final child support amount. Additional expenses that may impact child support include child care expenses, medical costs, home mortgage payments, tax filing status and other costs that determine the family’s financial situation. Generally, California courts require each parent to pay half of all child care expenses necessary for the custodial parent to obtain full-time employment.

    About the Author

    Heather Frances has been writing professionally since 2005. Her work has been published in law reviews, local newspapers and online. Frances holds a Bachelor of Arts in social studies education from the University of Wyoming and a Juris Doctor from Baylor University Law School.

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