Diane Lynn Kroupa (born October 12, 1955)[1] is an American attorney who served as a federal judge of the United States Tax Court from 2003 until 2014.

Following her criminal conviction in U.S. District Court for a tax-related crime (conspiracy to defraud the United States), she was sentenced to 34 months in prison.

Prior to appointment to the Tax Court, Kroupa worked for the Internal Revenue Service as attorney-advisor, Legislation and Regulations Division, Office of Chief Counsel.

On April 4, 2016, Kroupa and her husband, Robert E. Fackler, were indicted[4] on "conspiracy, tax evasion, making and subscribing false tax returns and obstruction of an Internal Revenue Service (IRS) audit" as a "result of an investigation conducted by the Criminal Investigation Division of the IRS and the United States Postal Inspection Service.

"[5][6] On October 21, 2016, Kroupa pled guilty to conspiring to defraud the United States for $450,000 in taxes.