I have also received two calls within 12 hours from this number (415) 878-3780 stating that they were the IRS and the call was time sensitive and that I need to call before actions are taken. I did return the call and advised them by leaving a message that I have contacted my attorney and the call will be turned over to Home Land Security and to never call my number again.
This # called my home and left an aggressive recorded message to call the irs back immediately or legal action would be taken within 12 hours. I called the # back and the "officer" I spoke to claimed I had ignored mailed notices and would have a warrent out for my arrest and my assets frozen if I did not settle my "claim" they had against me right then and there... No allotted time to contact my attorney, it had to be "settled" right then before disconnecting or else my file would be sent to the courts. I told them there was absolutely no way I was making any form of payment without speaking to my attorney and they said I had 5 mins to call back, at which time, I hung up and called my attorney and discovered this was in fact a malicious SCAM!!!