Child Dependancy Exemption

The custodial parent is entitled to the exemption for the dependent child for any divorce or separation parents.

There are certain exceptions which allow the non-custodial spouse to claim the exemption for the child:

The custodial parent releases the exemption of the child(ren) to the non-custodial spouse through the use of IRS Form 8332. In lieu of Form 8332, the IRS will accept a copy of the cover page of the agreement (with the custodial parent's social security number added), the specific clause unconditionally stipulating the exemption to the non-custodial parent, and the signature page showing the date of the agreement.
There is a pre-1985 divorce agreement, whereby a completely different set of rules and regulations are in effect.