Many identity thieves are using stolen Social Security numbers to file fraudulent tax returns. You won’t know whether you’ve been a victim until your tax return is rejected. Thinkstock By Sandra Block, Senior Editor From Kiplinger's Personal Finance, April 2016 If you believe someone has filed a tax return in your name—either because your return bounced back or you received a notice from the IRS about a suspicious filing—notify the IRS Identity Protection Specialized Unit at 800-908-4490. Next, go to www.irs.gov and download Form 14039, Identity Theft Affidavit. Mail or fax the form, along with a paper copy of your tax return, to the IRS (instructions are on the form). See Also: 8 Ways to Save on Your 2015 Tax Return If a delay in receiving your refund will create a severe financial hardship, contact the IRS Taxpayer Advocate Service at www.irs.gov/advocate, says Aaron Blau, an enrolled agent in Tempe, Ariz. The taxpayer advocate will intervene for taxpayers who demonstrate that their need is urgent, he says. When the case is resolved, you may receive an Identity Protection PIN (IP PIN) to use in the future when you file your tax return. If someone tries to file a tax return using your Social Security number and doesn’t include the IP PIN, the return will be rejected. You can also request a copy of the fraudulent return that was filed in your name. Some of the information will be blacked out, but the bogus return should help you determine how much of your personal information was stolen. The IRS has more information at this link. If you’ve been a victim of tax fraud, take other steps to prevent thieves from hijacking your identity. Contact one of the three main credit bureaus—Equifax, Experian or TransUnion—and have a fraud alert put on your account. (The credit bureau you contact will alert the other two.) For other tips, see 5 Great Tools to Prevent Identity Theft.