If the IRS receives two tax returns, each claiming the same dependent, they will contact the taxpayers involved and request documentation. The IRS will then determine which of the two taxpayers has the rightful claim. The process may take a few or even several months.
If your e-filed return is rejected because someone else already claimed the same dependent, you should resubmit your return on paper.
The right to claim a child as a dependent belongs to the custodial parent, which to the IRS is the parent with whom the child lived more than half the year. The IRS definition of "custody" has nothing to do with custody awarded by a local court.
**Answers are correct to the best of my ability but do not constitute tax or legal advice.
