Maybe they shouldn't have claimed you, but somebody used your Social Security Number and claimed you as a dependent. Most of the time, it's a parent who did this, but we have no way of knowing who it was.
If you are sure that no one else hast the right to claim you, there's only one thing you can do, and that is to print out your tax return and file it by mail. The IRS is going to keep rejecting your return if you keep trying to e-file.If you find out who claimed you, maybe you can get them to amend their tax return to remove you, but even if they agree, you'll still have to mail in your return.
Eventually, the IRS will open both returns, and decide who gets the exemption. So make sure that you are able to claim the exemption for yourself. If you reply with more information I can respond with the rules that may apply to your case.
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