Child support itself is not tax deductible to the non-custodial parent who pays it, and it is not taxable to the custodial parent who receives it. Nevertheless, the non-custodial parent may be able to get a tax break by negotiating with the custodial parent for the right to claim one or more children as dependants on their federal tax return.
Generally, according to the IRS rules, the custodial parent will be presumptively entitled to claim the child as a dependent, and for all purposes.
The non-custodial parent may be able to claim the child for a dependency exemption and the child tax credit (but not for the earned income credit) if all four of the following statements are true:
The parents: a. are divorced or legally separated under a decree of divorce or separate maintenance, b. are separated under a written separation agreement, or c. lived apart at all times during the last 6 months of the year, whether or not they are or were married.
The child received over half of his or her support for the year from the parents.
The child is in the custody of one or both parents for more than half of the year.
The noncustodial parent attaches a Form 8332 signed by the custodial parent.