Deductions & credits

The IRS is required to withhold the refund for the Child Support based on when the IRS issues the check.  It does not matter what year the Child Support was due, it just matters how much Child Support was due when the IRS issued the check.

On another note, if the child lived with him the entire year and he paid for over 50% of the child's support, he *IS* eligible to claim the child.