There are a number of steps to take, and I will give you a link below.Certainly for tax purposes, you need to contact the IRS. There is a form to fill out if someone else is using your SSN. Complete IRS Form 14039, Identity Theft Affidavit. Use a fillable form at An official website of the United States government, print, then mail or fax according to instructions.You also should call your local social security office.Here are other steps to follow:Identity Theft Information for Taxpayers and Victims