Authorities say Craig Haber was arrested Wednesday at his Manhattan apartment.
U.S. Attorney Preet Bharara (bah-RAHR'-ah) says Haber is accused of betraying his partners at Grant Thornton LLP by deceiving clients.
Authorities say Haber instructed clients between 2004 and last July to send checks to him rather than to the firm's headquarters.
The accounting firm says it immediately contacted authorities and cooperated fully with them.
Haber has been released on $500,000 bail. He could face up to 20 years in prison if convicted of mail fraud.
Defense lawyer Michael Bachner has declined to comment.