California, like all states, sets child support based upon a mathematical calculation, as now mandated by federal law. However, each state can, and does, come up with its own method of arriving at the child support payable by one parent to the other. In California, the formula is so complicated that it requires a computer program to determine the appropriate amount.
Several commercial companies sell these programs to attorneys and provide them to the courts free of charge to encourage the courts to use their product. The programs most typically used by the courts are DissoMaster and XSpouse.
For the most part, the most important inputs are both parents’ monthly income and the amount of time the child spends with each parent. Who has legal custody does not matter. For example, the custodial parent may sometimes be required to pay support to the non-custodial parent if the custodial parent earns substantially more and the non-custodial parent spends any appreciable time with the child or children. Issues like step-parent income and taxation can further complicate the calculation.
Because the amount of support ordered over time can be considerable, it is wise to have someone very knowledgeable about the support calculation prepare the figures before going to court. Busy judges do not have the time to “tweak” the computer calculation for self-represented parties. Even small changes in the amount of support paid can, over time, add up to hundreds and even thousands of dollars.