Child support is the legal mechanism requiring parents to share in the economic support of their children. Under the law, parents are obligated to support their children regardless of whether they reside with them. Support calculations for noncustodial parents are based on many different factors, which vary from state to state. Enforcement is the single biggest challenge in the area of child support. The federal government continues to pass laws enhancing states' enforcement capabilities. Recipients of child support differ by race and ethnic group. Child support obligations are distinct from alimony and are usually independent of parenting time.