Gretchen Sierra is a Principal in Deloitte's Washington National Tax-International Tax group. She advises U.S. and foreign-based multinationals on a broad range of international tax matters, including supply chain structuring, IP migrations, U.S. income tax treaties, inbound planning, financing transactions, cross-border mergers and acquisitions, and e-commerce transactions. Prior to joining Deloitte in January 2009, Ms. Sierra was Deputy International Tax Counsel in the Office of Tax Policy of the U.S. Treasury Department. As Deputy International Tax Counsel, she had responsibility for a broad spectrum of U.S. tax treaty and international tax regulatory and legislative matters, including the contract manufacturing regulations. Prior to joining the Treasury Department in 2005, she was Legislation Counsel for the Joint Committee on Taxation of the U.S. Congress, where she advised the House Ways & Means Committee, the Senate Finance Committee, and other members of Congress on proposed international tax legislation, including the American Jobs Creation Act of 2004. Ms. Sierra is an adjunct professor at the Georgetown University Law Center. She is also a coauthor of the Bloomberg/BNA Tax Management Portfolio Planning Matrix for U.S.-Based Multinational Corporations.