I received a call 7:05 AM MT on 1/20.  Message said that the IRS was going to file a lawsuit against me.  I was so surprised to get a call at that time that I didn't really get to hear what else was said.  Regardless, here's what let me know that this was a scam.  First of all, the IRS, if the IRS called, would use a toll free number that can be called back.  The IRS would never use a number other than a toll free number.  Second, when I called the number back, I received a "non-working number message", which was clue number two.  Third, the IRS would never call someone prior to the appropriate time that you are allowed to make a call.  Therefore, the IRS would NEVER call you at 7am MT.  Lastly, the IRS would not file a lawsuit, especially if they've not sent out any letter beforehand.  Definite scam.