You can file a tax return calming the personal exemption for the child by e-filing or mailing the tax return. If you have a tax refund the IRS will pay the tax refund.
If the IRS receives two or more tax returns claiming the same personal exemption they will contact each party sometine in the future to determine who was eligible to claim the exemption. The loser of the investigation gets to return any refund based on the exemption plus penalties and interest.
