In general, state law determines child support guidelines. After the gross income of both parents is totaled, certain deductions are allowed from each parent's income, (such as local income taxes already paid and child support paid to other children). Keep in mind that any court-ordered spousal support is included in the gross income of the recipient spouse, and is deductible from the gross income of the payor spouse.
Once the adjusted gross income of each parent has been totaled, these figures are applied to a chart which outlines the approximate support required to raise a child based on stated income levels. The court then requires each parent to pay his/her pro rata share of that charted amount.
For example, if the mother is earning $90,000 and the father is earning $60,000, the combined total is $150,000. If the charted amount states that $10,000 of child support is required each year, the father would be required to pay $4,000 of the $10,000 because he provides 40% of combined spousal income. Furthermore, the mother would be required to pay $6,000 because she contributes 60% of combined spousal income.
Once these payments are determined, the amounts can be changed; however, you will need to go through a similar process, just as when child support was first established. The parent requesting the change must file papers with the Court and prove that there are significant changes, beyond his/her control, which necessitate a change in the current arrangement.
Child support payments continue until the youngest child graduates high school or reaches age 18. Unless otherwise ordered, payments to a child over the age of 18 will continue to age 19 as long as the child attends high school. Special consideration is made to disabled children and children born out of wedlock.