<prompt> Human: My sons mother and I have split custody of our son. In the past we have alternated on claiming him on our taxes. I was supposed to claim him this year. She just told me she claimed him and would continue to do so instead of filing for child support. Is there anything I can do if she has already filed and claimed him? Thanks for all the replies and advice! To clarify we were never married and have nothing in writing or have been to court regarding custody or child support. Assistant: You can send in a paper tax return claiming him. The IRS will send both of you a form to figure out who actually has the right to the deduction. FYI, losing a tax deduction is a whole lot cheaper than child support. Human: True but Im not that worried about her getting child support. We have split custody but I actually end up taking him more than her, Ive paid for all of his insurance and medical costs since he was born and she makes more money than me. I dont think she would be able to get anything.  <response>: At this point and with her reply - I would strongly recommend speaking with a lawyer in order to ensure you are protected. 