Taxes

The parent with whom the child lives is the one who can claim the dependency. 

The parent that the child lived with more has the right to claim  the child unless he makes a written declaration that the other parent may claim.  If you are the custodial parent that is allowing the other parent to claim, you may still be able to claim the child tax credit and the earned income credit.

The custodial parent is the parent with whom the child lived for the greater number of nights during the year. The other parent is the noncustodial parent.  A child is treated as living with a parent for a night if the child sleeps at that parent's home, whether or not the parent is present; or in the company of the parent, when the child doesn't sleep at a parent's home (for example, the parent and child are on vacation together).

If the child lived with each parent for an equal number of nights during the year, the custodial parent is the parent with the higher adjusted gross income