Taxpayer refunds are sent out in batches via an expedited electronic system, Mr. Pine explained. If a refund is red flagged, it ought to prompt a closer examination by an I.R.S. employee who “should have immediately and proactively stopped the refund from being issued based on the obvious discrepancy between the income reported of $18,497 and the refund generated of $980,000.”

Mr. Blanchett has not been charged in federal court, Amy H. Filjones, a spokeswoman for the United States attorney’s office in Tampa, Fla., said on Friday. A date for the next hearing has not been set, said a spokesman at the United States attorney’s office.

According to court records, Mr. Blanchett pleaded guilty in 2016 to possession of drug paraphernalia and resisting an officer without violence, both misdemeanors of the first degree. In 2014, he was charged with possession of marijuana, also a first-degree misdemeanor, but the judge withheld adjudication, so he was not convicted of a crime.

SunTrust Bank, where Mr. Blanchett initially deposited the funds, suspected fraud and initially froze the funds, the court documents said, but later returned them to Mr. Blanchett via cashier’s check. He then put the money into an account at Grow Financial, telling the bank that the money came from the estate of his deceased father, the documents said.

Mr. Blanchett shifted the money around, transferring it among different bank accounts within Grow Financial, the complaint said, eventually using some of it to purchase a silver Lexus last August. On Friday, a spokeswoman for SunTrust and a spokesman for Grow Financial declined to comment.

The complaint didn’t specify when the I.R.S. first learned about the inaccurate refund check. But in August, Grow Financial sent the I.R.S. the funds in Mr. Blanchett’s account in accordance with a federal seizure warrant, the complaint said. The I.R.S. also seized the Lexus, and the government is seeking a car insurance premium of about $809 that was refunded to Mr. Blanchett when he no longer had possession of the Lexus.

During 2011 to 2013, when Mr. Pine served as the director of field operations for the eastern half of the United States, and in the years before, refund fraud was “out of control” in Tampa, he said, primarily because of identity theft.