According to the IRS rules, the custodial parent can claim a child as a dependent.   This opens the door to several tax perks, including an additional personal exemption, which reduces one’s taxable income.

The custodial parent is defined as the parent with whom the child spends the most time with.  But the custodial parent can agree to allow the noncustodial parent to take the tax break instead.

Both parents cannot claim the child.  Child support is deductible to the parent paying the child support.