What can I do if my ex wife is attempting to claim both children and we have a legal agreement to claim one child each every year?

[DavidD66]

If your ex-wife successfully e-files before you, and claims both children, you will not be able to claim either one on your tax return and e-file.  You can still claim one, however, you will have to print and mail your return.  In this case, the IRS will contact each of you to determine who is entitled to claim the child as a dependent.  For more information on whom you claim as a dependent see Rules for Claiming a Dependent on Your Tax Return