A Marietta man has been sued by the United States for filing fraudulent tax returns for others.

Robert Knupp of Marietta is accused of preparing large fraudulent federal tax refunds for customers. The Justice Department is seeking to keep him from filing and preparing returns for others, they said in a statement.

What may have triggered the government reaction is a tax return in which Knupp claimed a refund for a customer of more than $2 million, according to court papers.

The scheme Knupp is accused of, according to the Justice Department, “relies on false IRS Forms 1099-OID claims to report fictitious tax withholding on his customers' returns and then claims refunds of huge amounts.”

The Justice Department believes the scheme is part of a trend to file fake returns to steal from the U.S. Treasury.

“These schemes carry a high price -- steep civil penalties and, where appropriate criminal prosecution -- for preparers who promote them and for their customers who sign false tax returns,” said John A. DiCicco in a statement.

DiCicco, acting assistant Attorney General for the Justice Department, said taxpayers are to report any tax preparer who files fictitious returns. Instructions on how to do so are available at www.irs.gov.

The government estimates that in 2009 Knupp prepared or filed returns of approximately $11 million.