In general, the IRS code dictates which parent is allowed to claim a minor child as a dependent and receive the tax dependency exemption. The IRS code provides that the custodial parent is the parent who can claim the minor child on their tax return. A custodial parent is defined as the parent with whom the child lived for the greater number of nights during the year. The other parent is called the noncustodial parent. So, if your child lives with you the majority of time, then you are entitled to claim the child as a dependent.
The noncustodial parent can claim the minor child as a dependent if the parties enter into an agreement allowing the noncustodial parent to claim the minor child. In my experience, it's often common for parents to rotate claiming on child every other year. If the parties have more than one child, often they will each agree to claim one. If the noncustodial parent is allowed to claim a child pursuant to an agreement, it is not sufficient to simply attach the agreement to your tax return. You must have the custodial parent fill out form 8332. (If the agreement was entered into prior to 2008, then the agreement is sufficient).
If you have questions about claiming your children on your federal income tax return, contact your expert family law attorney today.