Child support or child maintenance is the ongoing obligation for a periodic payment made by a non-custodial parent to a custodial parent, caregiver or guardian, for the care and support of children of a relationship or marriage that has been terminated.

In family law, child support is often arranged as part of a divorce, marital separation, dissolution, annulment, determination of parentage or dissolution of a civil union and may supplement alimony (spousal support) arrangements.

Depending on the jurisdiction, a custodial parent may pay child support to a non-custodial parent. Typically one has the same duty to pay child support irrespective of sex, so a mother is required to pay support to a father just as a father must pay a mother.

In some jurisdictions where there is joint custody, the child is considered to have two custodial parents and no non-custodial parents, and a custodial parent with a higher income may be required to pay the other custodial parent.

In other jurisdictions, and even with legally shared residence, unless they can prove exactly equal contributions, one parent will be deemed the non-resident parent for child support and will have to pay the other parent a proportion of their income; the "resident" parent's income or needs are not assessed.