Dependency exemption
The parent who has custody of the child for the greater part of the year (the custodial parent) is generally treated as the parent who provides more than half of the child's support, and therefore, that parent gets the deduction. IT DOES NOT MATTER WHETHER THE CUSTODIAL PARENT ACTUALLY PROVIDED MORE THAN HALF OF THE SUPPORT.
The noncustodial parent will be treated as providing more than half of the child's support if:
1. The custodial parent signs a written declaration that he or she will not claim the exemption for the child, and the noncustodial parent attaches this written declaration to his or her return,
2. A decree or agreement went into effect after 1984 and states the noncustodial parent can claim the child as a dependent without regard to any condition, such as payment of support, or
3. A decree or agreement executed before 1985 provides that the noncustodial parent is entitled to the exemption, and he or she provides at least $600 for the child's support during the year, unless the pre-1985 decree or agreement is modified after 1984 to specify that this provision will not apply.
So, unless you qualify under the above rule, you are SOL.