I was told the same thing. When filing electronically, the system sees the SSN is used already for whatever reason and automatically rejects it. That's why they say you must email your return, so a human can interpret it. I had the same issue where I paid for the care 100% of my daughter who is separated, but since her husband filed "married filing separately", the IRS assumes they are both filing a tax return, because they're married, but they are each filing separately. So they are waiting on her (her SSN) to file a return, so it can't be used by myself. To me, it's a glitch in their system. The same with my 19-year old son. My ex was not supposed to claim him but did first, so I can't even claim him on my return and all of his college I paid for. So my only option is to electronically file as is, then file an amended return by paper with them on it, explaining why I have the right to claim them.
