Surprisingly, this question is relatively simple to answer for most cases. Please note that there are cases where this question is very complicated, and I will not address these cases here because I want this post to be simple and accessible to most parents. As always, nothing in this post should be construed as legal advice!
Broadly speaking, the amount of child support is a function of: 1) the number of children receiving support; 2) the percentage of time the children spend with each parent; and 3) the incomes of each parent. If you think about it, this makes perfect sense because: 1) 2 children are more expensive than 1; 2) A large percentage of custodial time costs more than a small percentage; and 3) the more income a parent has, the more they can afford to pay towards supporting their children. As a corollary, the less income a parent has, the more they will need.
Now, lets get down to specifics. The judge in your case will use special calculator software to determine the amount of child support. You can try out a similar calculator for free at this State of California website: https://childsupport.ca.gov/guideline-calculator/
The formula is called the “guideline” formula, but it is not actually a guideline—it is mandatory. So, since the formula is mandatory, why do parents fight over child support? It should be simple, right? Well, not really. While parents cannot fight the formula, they can and do fight about the numbers that go into the formula. Generally, the payor parent wants to minimize their income because the lower their income, the less support they will pay. The payee parent also wants to minimize their income because the lower their income, the more child support they will need.
Finally, in addition to the guideline amount, there are mandatory and discretionary add-on amounts.
The mandatory add-ons are: Childcare costs related to employment or to reasonably necessary education or training for employment skills, and the reasonable uninsured health care costs for the children.
The discretionary add-ons are costs related to the educational or other special needs of the children, including the cost of counseling, private school tuition, standardized test preparation, or special education classes; and travel expenses related to visitation. Both mandatory and discretionary add-ons are generally apportioned 50/50 to the parents.
That is California child support in a nutshell. Please be aware that there are certain circumstances where my analysis in this blog post will not apply. That is why you are best off speaking to a California family law attorney if you can afford to pay one.
-Ryan