IRS Scam:

The IRS does not need to sue anyone.  They send you first class letters delivered by the Post Office.  Several of them.  Ignore those, and they then send certified letters that you need to sign for.  Again delivered by the Post Office.  Ignore those and they simply freeze your bank accounts and anything else you own.  If they can do that, then why would they bother with a court case that might take them years before they get in front of a judge?  They also do not bother arresting people for a few thousand dollars for the same reasons I have already given.

Official IRS Government site detailing this scam and providing links to report it:
http://www.irs.gov/uac/Newsroom/IRS-Warns-of-Pervasive-Telephone-Scam
https://www.irs.gov/uac/Online-Scams-that-Impersonate-the-IRS
https://www.irs.gov/uac/Tax-Scams-Consumer-Alerts
https://www.irs.gov/uac/Newsroom/Phone-Scams- ... 6-Filing-Season
https://www.irs.gov/uac/Newsroom/IRS-Complete ... -Scams-for-2015

Fraudulent.  IRS Call.  DON'T FALL FOR THIS!

RoboCall:  Officer Daniel Wayman from the legal department of the IRS... In reference to a criminal lawsuit against me.  Reference number  CF93271. If they don't hear from me or my attorney, the only thing he can do is "wish me luck in the matter"...

The IRS would not call you, NOR file a criminal lawsuit against you.  Don't fall for this!

Said they were the IRS

Called me twice within 5 minutes and left a voice message claiming he was from IRS. Same case number as you guys had (two case numbers would never be the same). I tried calling back to see wat happens, but the number was busy.
This is total scam!

Same call, same case number. When I called back a voice with a strong [***] accent answered. He asked for information which I denied until he could tell me who I am, which he couldnt.