It can be a serious issue if someone other than you files a tax return in your name. The IRS offers resources to assist in cases where you believe it may have happened to you.
First, you should file an Identity Theft Affidavit (IRS Form 14039) as soon as possible to let the IRS know that someone is using your identity. You can also call the IRS at 1-800-908-4490.
If you received a 5071C Letter from the IRS, it means the IRS received a return with your name and/or Social Security number and suspects it may not be from you. The IRS sends this letter to verify your identity and confirm whether or not you submitted the return. If you received this form, you will need to contact the IRS.
If someone filed a return using your social security number, you will need to print and mail a paper return for that year.
If someone filed a return in your name, visit IdentityTheft.gov for tips to recover from identity theft. The IRS also offers Identity Theft Information for Taxpayers to help you understand your options.