If someone else has already claimed your child, then you will not be able to electronically file your return. However, you should still claim your child and mail your return to the IRS. You should also attach a statement explaining what has happened and also explain that you are the custodial parent and the one who has the right to claim the child.
Once the IRS receives your return, they will investigate to see who actually has the right to claim the child. If you are the child's parent and the child lives with you for most of the year, you will be awarded the exemption, and you will then receive your full refund. The other person will then be made to pay back any additional taxes and penalties that he owes.
Thank you hb
Hello again hb,
There is really nothing that you can do personally to prevent this from happening again.
However, if you follow the steps as outlined in my first response, then once the IRS rules in your favor, it is not likely this person would try the same thing again in the future. The IRS will let him know that he is not entitled to claim the child and they will not only make him pay back any additional taxes he owes as a result of his deduction being denied, he will also end up owing the IRS interest and penalties. That in itself should be enough to make him think twice about trying the same thing in the future.