I have the same problem right now with a customer. He says it may be possible his ex has claimed the son, he does not speak to her. However he has had legal custody for over five years, she signed away parental rights and hasn't seen the child in 4 years. He has not had this problem in the previous years. It's possible he has always filed before she had a chance to before? This is the first year he has waited til the last moment. He doesn't even know how to get in contact with her to ask her, if she would even be honest about it. Is there any way to find out the exact reason for the rejection, instead of just getting 'cause you need to fill out this form, which main purpose is for something that does not apply? I loathe the IRS, so many rules always changing.