William J. Kambas


  • 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
  • Admitted: State of CT, 2003 • State of NY, 2004
  • Year joined: 2006


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.  This includes planning for inbound and outbound business transactions, cross-border investments (whether made directly or through investment funds or joint ventures), qualification for US tax treaty benefits, and the US income and estate tax consequences associated with the ownership of US real estate by non-US persons.  It also includes assisting clients with responding to inquiries from US federal and state tax authorities.  Bill is admitted to practice before the United States Tax Court.

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 involved with Withers Bergman's 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 Charles F. Dolan School of Business, 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


  • 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.
  • "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

  • "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.
  • "US 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)

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. 

You are now leaving Withersworldwide and visiting Withers Consulting Group (WCG) website. Please note WCG does not offer legal services and is therefore not regulated by the Solicitors Regulation Authority or other regulating body. WCG works independently of Withersworldwide. For further information please see WCG's +Regulatory Notice +