Deductions & credits

Since you mentioned that you will not claim the child on your return and the child did not reside with you, who will not be able to claim any of the credits or deductions based on this child. 

Even though your legal agreement states that you have joint custody, for tax purposes there is no such thing as joint custody.  Instead, there is only the classification of "custodial" and "non-custodial" parent. To be custodial parent, the child must live with that parent more than half of the year. Because of this, one parent is always the custodial parent and the other the non-custodial parent.

The custodial parent has first priority on claiming the child for the dependency exemption, regardless of the amount of support provided by the non-custodial parentThe non-custodial parent can only claim the child as a dependent if the custodial parent gives permission (using Form 8332).  If the non-custodial parent is allowed to claim the dependency exemption, they then may be eligible for the Child Tax Credit. 

The non-custodial parent is never eligible for the Earned Income Credit, the Head of Household filing status or the Dependent Care Credit based on this child because of the Residency requirement for each of these tax breaks. 

Please see this helpful guidance from the IRS, which specifically addresses your situation in their first FAQ question: Divorced or Separated Parents

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