We were notified last year by our CPA that someone had used our mom's social security number.  Scary.  Tips we have been given by our financial advisor are to file as early as possible because IRS won't allow a second filing under a same social.  If you can't file early then get a PIN from IRS on IRS.gov especially if you file electronically. Remember to shred your stuff or keep your paperwork in a secure location and locked up!  If you are not efiling then hand carry your returns to the post office...don't just mail them from "wherever".  Alot of us have been victims of tax scams either thru email or by phone calls so don't give personal information to anyone unless YOU initiated the contact and if you have online accounts...monitor them.  Common sense right?  Yes, but we all get lazy don't we?  We are still helping my mom fight this issue.  Don't let your identify float down the river!