SCAM! Got the same call from the "IRS" today.  The following is from the IRS.gov web site:

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 don’t owe taxes, or have no reason to think that you do:
Do not give out any information. Hang up immediately.

Contact TIGTA to report the call. Use their “IRS Impersonation Scam Reporting” web page. You can also call 800-366-4484.

Report it to the Federal Trade Commission. Use the “FTC Complaint Assistant” on FTC.gov. Please add "IRS Telephone Scam" in the notes.
If you know you owe, or think you may owe tax:
Call the IRS at 800-829-1040. IRS workers can help you.