You may never find out who claimed your child. IRS will not reveal this information to you.
The person must be the parent or other close relative to claim your child. The old rule of merely paying more than 50% of the child's total income is no longer in effect.
If you would like to send me more information about the relationship to the child, and the child's payment of his own total support, I can help you further.
Master Tax Advisor, Enrolled Agent
I am a Master Tax Advisor and Enrolled Agent. I have 40 years experience. Trucking specialist.