William J. Kambas

Practice Areas

Bill is a partner in, and the Regional Division Leader of, the US private client and tax team at the international law firm, Withersworldwide. He focuses on tax planning for multi-national and multi-state personal, active business, and investment activities, with a particular emphasis on tax structuring and choice of business entity for US and non-US business owners and investors.

Bill has represented a variety of private and public interests, including family-owned, start-up, and multi-million dollar enterprises on purely domestic as well as inbound and outbound business transactions and cross-border investments (whether made directly or through investment funds or joint ventures). In particular, he has considerable experience advising on tax planning for US real estate investments (whether residential or commercial, development, operational, or for personal use). An integral part of Bill's practice involves assisting families and/or their family offices with the formation, management, and/or periodic evaluation of multinational and/or multi-generational centralized control and management structures, such as family offices and private trust companies.

Bill has participated in numerous speaking engagements, industry memberships, and publications. For example, Bill has been a guest lecturer at the Heckerling Institute, the Hellenic Studies Program at Yale University, the Columbia Business School's Family Business Program at Columbia University, the University of Connecticut School of Law, and the Charles F. Dolan School of Business at Fairfield University, as well as with the International Fiscal Association, American Bar Association, and the Society of Trusts and Estates Practitioners.

Bill has been recognized by a number of industry groups, including as one of the 21 People to Know When Starting a Family Office by Business Insider; one of the Top 100 Family Influencers by Family Capital Media; as a Fellow of the American Bar Foundation; as a “key lawyer” by The Legal 500 US in the area of international tax and not-for-profit in 2021 and 2020; as one of the Best Lawyers in the US for the years of 2021, 2020, 2019, and 2018; and as one of the Connecticut Law Tribune's New England Trailblazers for 2019. Bill is also a Fellow of the American College of Tax Counsel ("ACTC").