Its a scam that has been widely reported.the I.R.S. Never contacts you over the phone.you ate presented with legal documents if you are being investigated.never are you forced to pay over the phone.ask the person for their agent identification number,that will normally shut them up.report this to your state attorneys general.they are aware of this scam.
This person stated that they were calling from the US Treasury. He didn't speak English very well. When I called back, a woman answered, and she said that it was the us treasury. She sounded like someone with an Asian background. I gave them no information. People like this need to stop trying to scam people.