If these clowns call and threaten you, tell them to go ahead and carry out their threat. They won't as they're scammers, pure and simple.
I've had these type calls claiming to be from I.R.S. after I listen to their lies I inform them I'm a U.S. Treasury Agent and demand to know their IRS ID number, supervisor's name and unit number...they seem to be in a hurry to disconnect me...Ha!
Same thing when scammers call claiming they have a summons for me. I listen to their B.S. then inform them I'm an attorney and demand to know the docket number, who issued it, which county and state...they just hang up...Ha!