If he doesn't amend his return and pay back the ill gotten gains in about 18 months to 2 years you BOTH will get a letter telling you both that ONE of you filed incorrectly and needs to amend their return. If neither person does then in another 3 to 6 months you will both get another letter requiring you BOTH to prove you have the right to claim the child. The winner gets to keep the money ... the loser gets to pay back the money with penalties and interest added on AND the ability to claim the EIC taken away for up to 10 years.
