Usually, when the IRS denies your exemption for a child, it means that someone else filed before you did, claiming the same child as an exemption.  This usually arises when a stepparent and biological parent both claim the exemption. However, in today’s internet world, identity theft is becoming the reason more often.  Since you filed later, the IRS assumes you are the one not entitled to the exemption and you must then prove that you are entitled.  We do this by proving the child resided with you for more than 6 months using medical bills and school records for the child showing your address and establishing you as the custodial parent We also use affidavits from friends, neighbors and relatives showing that the child lived with you.  The second criteria is that you have to show that you provided more than 50% of the child’s support.  Once all of this proof is gathered, it will be submitted to the revenue officer in order to convince him that you are the one who can legally claim the child.