People are waiting for their tax refunds to arrive.  And when there's money to be had, there are scam artists.  Inspectors are warning of a scheme that is costing every one of us.

“They asked me if I had seen or noticed anything unusual in my neighborhood," explained Bob, the victim of fraud.

When asked if he had seen anything unusual, Bob answered, "Absolutely."

Bob will only reveal his first name as he discusses suspicious activity linked to a multi-billion dollar scam.  It starts with the theft of Social Security numbers belonging to residents of Puerto Rico.  It ends with major theft from the U.S. Treasury.

“Puerto Ricans generally do not file federal income tax returns, but they are issued Social Security numbers, so the fraudsters will steal the SS numbers, dates of births and bring them up here to the United States to file federal income tax return checks,” explained an undercover agent.

The con men direct the IRS to send the refund checks to an address of someone they know or to easily accessible mailboxes like the one at Bob's house.

“This came to my house, I had no idea who it was for and wrote return to sender right here and took it to the post office. I thought it was strange, because it came in September,” said Bob.

Inspectors say Bob did the right thing.

“We’ve intercepted billions of dollars in fraudulent federal tax return checks,” said the undercover agent.

Inspectors say they have done surveillance and undercover sting operations to arrest people in this scheme.

“We want our postal customers to inform us if they have received such type of checks in their mailbox,” the undercover agent added.

The scam cost the United States $6.2 billion last year alone.  Taxpayers are victims in the scam, along with the victims whose identity was stolen.  Postal Inspectors say Puerto Ricans are not alone.  Citizens in Guam are now also finding their information compromised.