US Department of Treasury Warns Taxpayers About a 'Frightening' Fraud Scam Taxpayers should be on high alert over fraud scam this season.

 -- With tax season upon us, the U.S. Department of the Treasury is warning taxpayers to be on high alert for a frightening fraud scam.

People pretending to be International Revenue Service (IRS) agents are making ruthless, aggressive calls, telling people they owe back taxes and threatening them if they don’t pay up immediately.

“I am going to proceed you to the sheriff's officer. And within the next hour they will be at your doorstep to handcuff you and put you behind bars,” a fraudulent caller told ABC News.

Deputy Inspector General for Investigations at TIGTA (Treasury Inspector General for Tax Administration),Timothy Camus has received reports of nearly 900,000 fake calls since October 2013. Roughly 5,000 victims have paid over $26.5 million as a result of the scam.

With the epidemic growing, TIGTA has released video public service announcements for the first time, that are available in English and in Spanish, warning taxpayers about the scam, urging them to “hang up on fraud.”

Click here to see the PSA campaign.

They say the real IRS never threatens, never calls asking for immediate payment or your credit card number, and will always send a letter first, if back taxes are owed.

But fraud tactics are evolving.

“These guys have changed over a period of time, where they just call out of the blue, and so as we’ve been warning people, that the first contact will not be by telephone. Part of the script now is, ‘oh we’ve been sending you letters that you’ve been ignoring,’” Deputy Inspector General for Investigations, tells ABC News.

However,“they’re changing their game as we’re putting out information on what to be aware of. But the one thing that has not changed, is the threat of immediate incarceration if you don’t pay the money,” he said.

Editor's Note: Timothy Camus' title has been revised from an earlier posting of this story.