If you're sure you're right, print your tax return (claiming yourself) and mail it in. Don't e-file it. When the IRS receives two tax returns each claiming the same social security number, they will contact both taxpayers and ask for supporting information. Then they will determine who has the right to the claim according to IRS rules. Winner gets the exemption; loser gets billed for the additional tax, plus penalties if any. This all may take a while of course.
**Answers are correct to the best of my ability but do not constitute tax or legal advice.
