According to the New York Daily News, Schenjer Zalman (A.K.A., "Jimmy") Gurary, a Chabad rabbi and "garment center executive" who was at one time one of the leaders of Agudas Chasidei Chabad (Aguch), owes…
…New York State $3,421,194 in back taxes. (I'm not sure, but I think this would be his estate, but I hope I'm wrong.)
According to the Daily News, Jimmy Guray went to prison in 1988 for "a phony billing scheme that helped 170 firms and individuals - including himself - evade $130 million in taxes."
Gurary's daughter and son-in-law, Esther and Rabbi Nocham Sternberg, who were both involved in the tax fraud, refused to testify against Gurary, telling federal officials it was against their religion to 'moser,' inform, on another Jew.
They were found in contempt of court. Both later served time, I believe.
Here is Jimmy Gurary's losing appeal to the US Supreme Court:
[Hat Tip for the Daily News piece: Archie Bunker.]