Is that really the Internal Revenue Service knock, knock, knocking on your door? That's a concern shared not just by individuals who find people claiming to be with the federal tax collector's office, but also the IRS itself. "Many taxpayers have encountered individuals impersonating IRS officials – in person, over the telephone and via email," noted the IRS in a statement issued this week. In-person tax scams: While email phishing attempts and the still pervasive fake IRS agent telephone tax scam are still going strong — and could even see a surge as the cons are tweaked to incorporate the...