What can I do if someone claimed my child and they weren't supposed to?

[VolvoGirl]

Just file your return and the IRS will determine who is able to claim them.  If they file first and your return rejects you will have to print and  mail your return.  

[xmasbaby0]

If the other person files first, your return will be rejected and you will have to file by mail and let the IRS sort out the duplicate use of the child's SSN.

When you mail a tax return, you need to attach any documents showing tax withheld, such as your W-2’s or any 1099’s.  Use a mailing service that will track it, such as UPS or certified mail so you will know the IRS/state received the return.

Federal and state returns must be in separate envelopes and they are mailed to different addresses.  Read the mailing instructions that print with your tax return carefully so you mail them to the right addresses.