You are talking about claiming for tax purposes as a dependent. Your ex is supporting the child, and you already have an agreement about this, so he is entitled to claim the child according to the agreement. Have another child with his new significant other gives him more expenses and another dependent, which has nothing to do with you.

If the claiming of the child on income taxes is a Court Order, you have to follow the order in place, otherwise you are in violation. As of right now follow what the courts have put into the child support order, you'll need to go back to court if you want this changed. However with him paying child support as well, it really shouldn't be a big deal that he gets a decent return every other year. Especially when you receive child support for the whole year and he only gets to see the child once a week.

The best thing I can tell you is that to find yourself a good family court lawyer. Look at the laws in your relevant state yourself and try and decide if it can be handled outside of the court without an attorney or not. Try and reason with him and see if he would be willing to agree to the terms of you claiming your child every year. But even if he does get something in writing or an official document stating this. I have gone through a tough custody battle myself and have full custody of my son I can tell you the more you have on paper the easier things can go later down the line if that person tries to makes things difficult for you. Hope this helps. J.