The Internal Revenue Service watchdog on Thursday warned taxpayers of a sophisticated nationwide phone scheme that has become “the largest scam of its kind that we have ever seen.”

The plot involves callers claiming to represent the IRS and demanding immediate payments with a pre-paid debit card or wire transfer.

Treasury Inspector General Russell George (AP Photo/Charles Dharapak)

Treasury Inspector General for Tax Administration Russell George announced that “thousands of victims” have already paid more than $1 million to fraudsters and that his agency has received more than 20,000 reports of contact.

The callers have used roughly the same scripts to bilk money from taxpayers, suggesting they may be connected, TIGTA officials said in an interview with reporters.

Officials also said the perpetrators often know the last four digits of the victims’ Social Security numbers and threaten arrest, deportation and removal of driver’s licenses — something the IRS is not authorized to do.

“If someone unexpectedly calls claiming to be from the IRS and uses threatening language if you don’t pay immediately, that is a sign that it really isn’t the IRS calling,” George said in a statement.

The callers tend to use common names and fake IRS badge numbers, in addition to manipulating their caller ID to appear more legitimate, according to officials. Some also follow up with false IRS e-mails and phone calls in which they pretend to represent the police or department of motor vehicles officials, TIGTA said.

The IRS generally contacts taxpayers first by mail or with personal visits by field agents, and the agency does not accept credit card information by phone, according to TIGTA officials.

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