William J. Kambas

Regional Practice Group Leader, US Personal Income Tax Group

  • Education: Skidmore College, B.A. • University of Connecticut School of Business, M.B.A. • University of Connecticut School of Law, J.D. • University of Connecticut School of Law, Certificate in Tax Studies
  • Admitted: State of CT, 2003 • State of NY, 2004
  • Year joined: 2006
  • Year became partner: 2014


Bill’s practice is focused 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. He has represented a wide variety of private and public businesses including family owned, start-ups and multi-million dollar enterprises on purely domestic as well as inbound and outbound business transactions, cross-border investments (whether made directly or through investment funds or joint ventures), and qualification for US tax treaty benefits. In particular, Bill has considerable experience advising non-US persons on the US income and estate tax consequences and tax planning associated with the ownership of US real estate (whether residential or commercial, developmental, operational, or personal use). Bill is also admitted to practice before the United States Tax Court and assists clients with responding to inquiries from US federal and state tax authorities.

An integral part of Bill's practice involves working with families, their family offices, and/or family enterprises to assist with the formation, management, and/or periodic evaluation of multi-national and/or multi-generational centralized control and management structures.

Bill is a co-chair of Withers Bergman's Family Enterprise (including Family Business and Family Office) Special Interest group and was formerly active with the International Corporate Tax Group.  He is also a member of the firm's Pro-Bono Committee. 


  • Executive Committee, International Fiscal Association (Westchester, NY and Connecticut Region).
  • Guest lecturer at Yale University, Columbia Business School, University of Connecticut School of Law, Fairfield University. 
  • Member of the Committee on US Activities of Foreigners and Tax Treaties, Section of Taxation, American Bar Association and Subcommittee on FIRPTA (concerning the US taxation of real estate under the Foreign Investment in Real Property Tax Act of 1980).

Publications and speaking engagements


  • Co-Author, "How U.S. Persons Can Be Made Public by the UK Register," Estate Planning, August 2017.
  • Quoted, "New York Banking Royalty's Heirs Are Unloading Art to Save the Family Estate," Bloomberg, April 2017.
  • "A Mediterranean Comparison: Next Steps of FATCA and Global Data Exchange," Offshore Investment, Issue 260, October 2015.
  • "Aircraft Operations: Tax Tips For Avoiding Turbulence in Private Aircraft Operations," Estate Planning, August 2015.
  • "Like-Kind Exchange Can Help Foreign Investors Reach Goals," Estate Planning Journal, July 2015.
  • "Taxpayers Wynnes: Refund Opportunity for New York City Residents," June 2015.
  • "Assessing US Tax Consequences of a Departure from the Euro," Lexis Federal Tax Journal, March 2015.
  • "When in Rome...Pointers for US, UK, and Russian Buyers of Italian Property," STEP Journal, November 2014. 
  • Chapter co-author, The Complete Family Office Handbook: A Guide for Affluent Families and the Advisors Who Serve Them, January 2014.
  • “Structure and Integration: The Architecture of Succession,” Family Firm Institute, FFI Practitioner, August 2013.
  • “Global Mobility: U.S. tax considerations associated with obtaining a green card," Trusts & Estates, August 2012.
  • "Cross-Border Business Should Benefit From Malta's User Friendly Tax System and US-Malta Income Tax Treaty," LexisNexis® Tax Law Legal Newsroom and Withers Bergman LLP Briefing Notes, August 2011.
  • Contributor to "Ideas for Greece: International Entrepreneurship for Economic Growth," Odyssey Magazine, 2010 Year-End Issue.
  • "Small Business Jobs Act of 2010," LexisNexis® Tax Law Legal Newsroom and Withers Bergman LLP Briefing Notes, October 2010.
  • "Taking Effect 2010: The Evolving Landscape of US Income Tax Treaties," Withers Bergman LLP Briefing Notes, September 2010.
  • "Cross Border Philanthropy: Why is Doing the Right Thing Never Easy?", STEP U.S.A. Issue 10, November 2009.
  • "Update on the 2009 U.S.-France Protocol: Potential Significant Changes in the U.S.-France Income Tax Treaty," LexisNexis® Tax Law Legal Newsroom and Withers Bergman LLP Briefing Notes, October 2009.  
  • "Ratification by the Italian Parliament of the 1999 U.S.- Italy Income Tax Treaty Paves the Way for Entry into Force," Withers Bergman LLP Briefing Notes, July 2009.
  • "Giving to Greece: The Challenge of Cross-Border Philanthropy," Odyssey, May/June 2009.    
  • “Corporate Income Tax Nexus What Constitutes Doing Business in Connecticut?" Lexis CT Tax P.I. 2,978 (2007).
  • "Tax Consequences of Post-Merger Net Operating Losses," Lexis CT Tax P.I. 2,385 (2007).
  • "Taxation of Income from the Cancellation of Debt," Lexis CT Tax P.I. 2,384 (2007).
  • "Connecticut Restrictions on the Deductibility of Interest Expenses," Lexis CT Tax P.I. 2,383 (2007).
  • "Connecticut Dividends Received Deduction," Lexis CT Tax P.I. 2,845 (2007).
  • "Connecticut Restrictions on the Deductibility of Royalty and Intangible Expenses," Lexis CT Tax P.I. 2,382 (2007).
  • "Tax Credit for Financial Institutions," Lexis CT Tax P.I. 2,846 (2007).
  • "Tax Reform and Modernization," 108 Tax Notes 1447 (2005).
  • "Uncle Sam Sneaks a Peak Data Mining in Tax Compliance," 26 Nat'l. L. J. 42 (2004).
  • "The Development of the U.S. Banking System From Colonial Convenience to National Necessity," 28 RUTGERS L. REC. 4 (2004).
  • "The EU Safe Harbor Principles Offer Comprehensive Privacy Protection," 9 ILSA J. Int'l. & Comp. L. 149 (2003).
  • "Protecting Debtor's Subsidiaries Extending the Automatic Stay of 11 U.S.C. 362 To Foreign Subsidiaries," 17 Conn. J. Int'l. Law 127 (2002).

Speaking Engagements

  • "Greek Family Firms: Exploring the Logic and Dynamics of the International Shipping Enterprise" Yale University, The MacMillan Center, Hellenic Studies Program, with Elian Kulukundis, May 2017.
  • "Encouraging Engaged Ownership through Legal Architecture," International Association of Attorneys for Family-Held Enterprises ("AFHE"), Miami, FL, April 27. 2017.
  • "Direct Asset Investment/Real Estate Investing for Family Offices," Peltz International Family Office/Hedge Fund Semiar Series, New York, December 2016.
  • "The Impact of Tax Planning on the Flow of Funds within Global Companies," in Eurozone Crisis (Economics), Yale University, October 2016.
  • "Structuring the Global Family Enterprise for Performance and Economic Efficiency," STEP Wyoming International Estate Planning Conference 2016, Jackson Hole, WY, October 2016.
  • "Emergence and Role of Family Offices," Expert Webcast Panelist, September 2016.
  • "Planning the Estate: International Planning Considerations," in Family Business Management, Columbia Business School, New York, August 2016.
  • "US Taxation of Resident and Nonresident Aliens" Surgent Tax Webinar, July 2016. 
  • "Planning the Estate: Integrating Tax and Estate Planning" in Family Business Management, Columbia Business School, New York, June 2016.
  • "Taxation of U.S. Individuals Working and Living Overseas," Surgent Tax Webinar, June 2016.
  • "Engaging the Next Gens of the Family Office: Recreating and Preserving Family Wealth," Landmark Family Office Forum, New York City, May 2016.
  • "Current Developments Regarding the Use of Partnerships in International Transactions," International Fiscal Association, Stamford, CT, April 13, 2016.
  • "Joining the Family Business," Columbia Business School, Family Business Club, New York, March 2016.
  • "Alternative Investments for Best Returns: Income Tax Considerations," Landmark Venture Forum, Greenwich CT, February 2016.
  • "Maximizing the Bottom Line Return: Tax Considerations for Investments by Family Enterprises," Landmark Angels & Tech Coast Angels Venture Forum, Newport Coast CA, October 2015.
  • "Attributes of a Family Enterprise: Utilizing the Asset Holding Structure to Facilitate Business and Operational Succession," Family Office and Private Wealth Forum, Newport RI, July 2015.
  • "Family Office 2015 Outlook," Landmark Venture Forum, Greenwich CT, December 2014.
  • "Family Office Investing: Tax and Regulatory Considerations," Landmark Venture Forum, Greenwich CT, September 2014.
  • "Wealth Transfer Planning," Lecture at Charles F. Dolan School of Business, Fairfield University, April 2014.
  • "The Transfer Pricing Problem," in International Taxation, University of Connecticut School of Law, April 2014.
  • "Taxation of Gain on a Sale, Exchange or Disposition of a US Partnership Interest by a Non-US Partner,” International Fiscal Association (IFA), USA Branch, Westchester County, NY/Connecticut Region (Greenwich, CT), May 2013.
  • "Wealth Transfer Planning," Lecture at Charles F. Dolan School of Business, Fairfield University, April 2013.
  • "U.S. Tax Aspects of International Real Estate Financing After Navigating the Fiscal Cliff," New York City Finance Expo, April 2013.
  • "U.S. Tax Aspects of International Real Estate Financing," New York City Finance Expo, March 2012.
  • "New Frontiers in Estate Planning: Changing Laws and the Modern Family," The Woman's Club of Greenwich, January 2012.
  • "Families, Family Offices and Real Estate," New York Real Estate Expo, November 2011.
  • "Moving Across the Pond: Legal Considerations for Expanding to New York," London to NYC Forum sponsored by New York City Economic Development Corporation, December 2010.
  • "Foreign Investment in US Real Estate: Challenges and Opportunities," New York Real Estate Expo, November 2010.
  • “Themes in Taxation during the Election Season,” Exit Planning Exchange (XPX Connecticut) and The Association for Corporate Growth (ACG) Joint Event, Hartford, Connecticut, October 2010.
  • “Taxation of US Corporations with Foreign Income” and “Taxation of Foreign Corporations doing business in the US,” National Business Institute (NBI), New Haven, Connecticut, June 2007.



  • American Bar Association
  • Connecticut Bar Association
  • New York State Bar Association
  • International Fiscal Association
  • Hellenic Bar Association of Connecticut (Board of Directors)
  • Hellenic Lawyers Association of New York
  • Hellenic-American Chamber of Commerce (Member of the Committee on Finance, Investments, and Insurance)

Philanthropic Activities

  • Chairman, Skidmore College Annual Fund ("The Skidmore Fund") for the class of 1996 (2013-present)
  • Chairman, Saint Barbara Greek Orthodox Church Endowment Fund (2012-present)

On a personal note

Between work and family, Bill enjoys contemporary fine arts and ceramics as well as the art and archaeology of Minoan Crete and Ancient Greece. 

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