The following is quoted directly from the IRS website
“An aggressive and sophisticated phone scam targeting taxpayers, including recent immigrants, has been making the rounds throughout the country. Callers claim to be employees of the IRS, but are not. These con artists can sound convincing when they call. They use fake names and bogus IRS identification badge numbers. They may know a lot about their targets, and they usually alter the caller ID to make it look like the IRS is calling.
Victims are told they owe money to the IRS and it must be paid promptly through a pre-loaded debit card or wire transfer. If the victim refuses to cooperate, they are then threatened with arrest, deportation or suspension of a business or driver’s license. In many cases, the caller becomes hostile and insulting.
Or, victims may be told they have a refund due to try to trick them into sharing private information.
If the phone isn’t answered, the scammers often leave an “urgent” callback request.
The IRS will never:
Call to demand immediate payment, nor will the agency call about taxes owed without first having mailed you a bill.
Demand that you pay taxes without giving you the opportunity to question or appeal the amount they say you owe.
Require you to use a specific payment method for your taxes, such as a prepaid debit card.
Ask for credit or debit card numbers over the phone.
Threaten to bring in local police or other law-enforcement groups to have you arrested for not paying.
If you get a phone call from someone claiming to be from the IRS and asking for money, here’s what you should do:
If you know you owe taxes or think you might owe, call the IRS at 1-800-829-1040. The IRS workers can help you with a payment issue.
If you know you don’t owe taxes or have no reason to believe that you do, report the incident to the TIGTA at 1-800-366-4484 or at www.tigta.gov.
If you’ve been targeted by this scam, also contact the Federal Trade Commission and use their “FTC Complaint Assistant” at FTC.gov. Please add "IRS Telephone Scam" to the comments of your complaint.
Remember, too, the IRS does not use email, text messages or any social media to discuss your personal tax issue involving bills or refunds. For more information on reporting tax scams, go to www.irs.gov and type “scam” in the search box.
Additional information about tax scams is available on IRS social media sites, including YouTube http://www.youtube.com/irsvideos and Tumblr http://internalrevenueservice.tumblr.com, where people can search “scam” to find all the scam-related posts.”