Just as you support your children financially while you're married, you must continue to do so when you divorce. The major difference is that if you divorce, the government keeps a watchful eye on whether you're paying – at least if you're the non-custodial parent. Child support is designed to ensure that your children enjoy the same standard of living as they would have enjoyed if you and your spouse didn't break up.
What Support Covers
Child support contributes to the costs of your children's basic needs, including food, clothing and shelter. Depending on where you live, the court may expect it to pay for other things as well. For example, in California, it can cover things like toys, recreation and lessons. The logic is that because your children would have had these things if you had stayed married, you should contribute to them after your divorce.
Custodial Parent's Contribution
It's a misconception that custodial parents don't pay support. If your spouse has physical custody, she'll use her income toward the mortgage, utilities, groceries, and your children's other needs. Your child support payments contribute and defray some of these expenses. Your spouse pays her share directly to your children's needs.
Effect of Joint Custody
If the court awards you joint physical custody, this may cut down on your child support obligation. That's because most courts consider that both you and your spouse are paying for your children's needs directly when they're with each of you. If you earn considerably more than your spouse, you might have a small child support obligation, designed so your children can enjoy the same standard of living in both homes.