In the divorce decree it states that I, the dad, is to claim our son and she can claim our daughter. I lost my job and got backuped on child support and she put a lien on my taxes and then removed it recently because I had been paying. But now she has gone behind my back and claimed our son. She has a son from a previous marriage which she also claims, so claiming my son would be child 3 and she doesn't get much for him. I wanted to use the money I would get for him to put more money on the backed child support which I did let her know previously. What can I do? Would I get her in big trouble with the IRS if I claim our son? Or would she just have to payback the money she got from him since the divorce decree states he is mine to claim? I don't think she should be able to get away with this.

If the divorce decree does not state that you must be Up-to-Date with your child support in order to claim your son as an exemption, and if it gives you that exemption every year (not just odd or even years, or if you are earning a certain amount of income that year), then she had no right to take the child as her exemption. As you can see, the details are important.  Check the "qualifying language" in your Decree to make sure you are covered on all bases. If you NOW file your taxes and take your son as an exemption, the IRS is going to demand proof that you can do so -- you'll need to send a certified copy of your Divorce Decree to them. They already have someone claiming the child, so you will get a letter informing you that it is not allowed and what you can do to challenge the decision. They will review it, and let her know that they are assessing fines and interest on the amount of money she got back as a result of taking your son as an exemption.  In my experience, they have never put someone in jail for this, but they will make them repay it with interest and penalties.  If you did not file this for Tax Year 2010 because this is the first response to your question you have received, you can go back and file an Amendment now.  Hope this helps. Danielle D. D'Eor-Hynes, Family Law Center, LLC www.hynesfamilylaw.com