When in doubt check it out. Call the actual IRS number 1-800-829-1040. According to the IRS website IRS.gov they will not initially contact you by phone. They will mail a letter to notify you and give you an opportunity to appeal. The website states they will NEVER threaten to have you arrested or threaten a lawsuit. This is a SCAM people! Use your head and DO NOT GIVE THEM ANY PERSONAL INFORMATION!!!!!!