The calculation of child support is a relatively objective process based on the Federal Child Support Guidelines. The most important factors are the number of children and the income of the person paying child support. Income is usually determined by referring to recent tax returns, but sometimes additional information is required.

Sometimes there are special expenses associated with a child, such as medical or dental expenses, or expenses associated with extra-curricular activities. For such expenses, parents are expected to contribute in proportion to their respective incomes, and regardless of which parent has custody. For example, if a dental bill for a child costs $1000.00, and the mother makes twice as much as the father, the mother will be expected to contribute twice what the father contributes. In this example, the mother will contribute $666.67 and the father will contribute $333.33.

Often such expenses can be avoided if a parent registers a child in a benefit plan offered by the parent's employer.