Exwife claimed my child as dependent even though she lived in my house and I supported her for most of 2016.

[ript2damax]

However, she moved out and took all her information as well. What would be the best course of action?

[xmasbaby0 · Accepted solution]

If someone else claimed your dependent already, then your e-filed return will be rejected.  Print, sign and mail your own return which claims your dependent.  Mailed returns are processed differently by the IRS.  It will take some time (maybe even up to a year) but eventually the IRS will contact both parties and sort out who could rightfully claim the dependent.  The person who wrongfully claimed the dependent may face repayment of refund $, plus penalties.