Calculating Child Support in a California Divorce

The child support formula is in Family Code Section 4055. The formula takes the parents’ custodial time and their total net disposable income to calculate support. Net disposable income is the money you have after you paid taxes.

You can figure out your net disposable income by subtracting the taxes you owe, but adding back income for any tax deductions like health insurance premiums, mandatory union dues, and retirement benefits. Since your deductions reduce your taxes, you won’t be able to figure out

your net income just by looking at your pay stub, and you cannot use your gross income. If you do, the child support amount will be wrong and result in a larger support amount.

Calculating Child Support in a California Divorce


Since it’s hard to figure out the net disposable income, the easier approach is to use a California-approved support calculator which uses your gross income. Your gross income is the income you receive before taxes. You complete the calculator by inputting gross income, tax deductions, and custodial time. After completion, the calculator will provide you with your net disposable income and guideline child support amount. A much easier and more reliable approach.


You can use either the free-approved calculator or a paid version. The free support calculator is on the California Child Support Self-Service webpage provided by the California Department of Child Support Services. This is a good calculator to use, especially if you are doing the divorce on your own. If you are going to use this calculator, take time to review the User Guide located at the site. The User Guide has a lot of useful information and explains each part of the calculator in detail, including how to input varying kinds of income and tax deductions. In the next chapter, I explain what information goes into the calculator and how to complete it.


DissoMaster Calculator:

The other option is to pay for a California-approved software program or pay a divorce professional to prepare a calculation for you. The programs are expensive but can be very useful for more complex income or tax issues. The paid-for calculators also have more functions than the State program. You can easily change amounts, save reports, and review in a more convenient format. Alternatively, divorce professionals will have one of these programs and be able to run a calculation for you. The most common is the DissoMaster Calculator by Thomson Reuters.


Whichever version you use, the most important part is that you put the right information into the calculator. Otherwise, you will get the wrong child support amount.With any child support agreement, you are required to attach the calculator print-out to show the guideline child support amount or provide the information used to calculate the guideline amount.

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