I got this call too...I called them back and told whoever (in the call center) answered that they should either arrest me or leave me alone..he hung up on me...and hasn't called back...
"I need you to leave your work aside and dial the number to the Department of tax crime division. The number is 202-602-0405. I repeat it's 202-602-0405. As of as a matter of urgency. I'm looking forward to speak to you. Thank you. Goodbye."
They've been calling our home number three times a day with that exact same ridiculous message. It's designed to intimidate the elderly. Pay ZERO attention to it, except to block the number if your phone has that capability.