Social Security Identity Defense Act of 2013 - Amends the Internal Revenue Code to require the Secretary of the Treasury to make certain disclosures to the holder of a social security account number and to the Federal Bureau of Investigation (FBI) if the Secretary determines that there is a substantial likelihood that there has been a fraudulent use of such account number in the employment context. Authorizes the FBI Director to disclose information received from the Secretary to federal, state, and local law enforcement officials, but restricts the use of such information to carrying out criminal investigations or prosecutions.

Requires employers who have been notified of suspected misuse of an employee's social security account number to cease including such account number on statements provided to such employee.