There is no way of telling which dependent was used on another person's tax return and the IRS will not tell you. The usual suspect is an ex-spouse. If this is not the case, it is possible that someone else used your dependent's social security number to file a fraudulent tax return. In either event, you will not be able to efile your tax return because someone has already used your dependent's SSN. The only option you have is claim your dependent and then paper-file your 2016 tax return. To do this, you would select Paper-File instead of Efile when you are in
the File section after completing your return. Then
print, sign, date and mail your tax return by April 18, 2017.
