http://www.irs.gov/uac/Tax-Scams-Consumer-Alerts
Note that the IRS will never: 1) call to demand immediate payment, nor will the agency call about taxes owed without first having mailed you a bill; 2) demand that you pay taxes without giving you the opportunity to question or appeal the amount they say you owe; 3) require you to use a specific payment method for your taxes, such as a prepaid debit card; 4) ask for credit or debit card numbers over the phone; or 5) threaten to bring in local police or other law-enforcement groups to have you arrested for not paying.
Just as a follow up here is some info:
http://www.irs.gov/uac/Tax-Scams-Consumer-Alerts
Note that the IRS will never: 1) call to demand immediate payment, nor will the agency call about taxes owed without first having mailed you a bill; 2) demand that you pay taxes without giving you the opportunity to question or appeal the amount they say you owe; 3) require you to use a specific payment method for your taxes, such as a prepaid debit card; 4) ask for credit or debit card numbers over the phone; or 5) threaten to bring in local police or other law-enforcement groups to have you arrested for not paying.
Caller: Danny Watson
Company: IRS