Same as the others, said they were with the IRS, asked if I knew what this whole case was about.  I laughed and said I knew they were a scam.  The lady said okay, just hang up then and she'll show me how much of a scam they are.  I said, okay, thanks and hung up.

IRS SCAM. the irs doesn't call you

Scam. Saying I owe the IRS money. I have my taxes done by a professional.

How do I report these very annoying calls and prevent them??

Your fellow commentor Jeff appears not to represent any authority. The real IRS and the Federal Trade Commission should be happy to take your reports. The FBI's Internet Crime Complaint Center may also take interest. Look at your state attorney general and any other agencies. There's the easy part. Prevention is a long game with no clear winners. You would have to locate and smoke out the fiends in litigation. They don't make it easy and usually hide behind fake names and international borders.

The other thought I have is undeveloped. What attracts the calls in the first place? Knowledge of past credit problems? The fake IRS goons tend to play the same ruse as fake payday loan collectors, often with the same slightly revised scripts.