Professor Williamson, the Kogod Eminent Professor of Taxation and the Howard S. Dvorkin Faculty Fellow, teaches a number of subjects related to taxation, is director of the Masters of Science in Taxation degree program, and serves as executive director of the Kogod Tax Center, a research institute focusing upon the interests of small business.
He has also served as Adjunct Professor of Law at American University's Washington College of Law. Professor Williamson previously served as senior manager for international taxation at the National Tax Practice Office of KPMG in Washington, D.C., and as Professor-in-Residence at KPMG's Washington office. A certified public accountant, Williamson is a frequent lecturer to professional groups throughout the United States, and has held teaching appointments in Europe and China. He has published over 75 articles in professional and academic journals being recognized by the Bureau of National Affairs as its outstanding author for 2007; by the AICPA for its best article award in Tax Adviser (2011) and by Tax Analyst, Inc. as one of its Persons of the Year (2012).