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Ada Ko, with over 31 years of legal experience, counsels domestic and international clients on the tax aspects of corporate transactions, including mergers and acquisitions, financing, joint ventures and other business operations. Her practice emphasizes the tax implications of cross-border business operations and investment transactions. Ada was formerly Tax Counsel to the city of Seattle in the state of Washington. She has successfully tried tax cases before administrative and judicial tribunals.

Ada is active in the legal community and is a Past-President of the Tax Section of the Washington State Bar Association. She is also an officer with the Inter-Pacific Bar Association. In addition, Ada is an adjunct professor at the University of Washington Law School’s Graduate Tax Program.

Representative Transactions

  • Acts as external U.S. general counsel to one of the world’s largest manufacturers of fitness equipment.
  • Provides U.S. tax advice to foreign governments and foreign public sector pension funds investing in the United States.
  • Provides public and private companies advice in structuring their cross border mergers and acquisitions.
  • Provides U.S. tax and corporate advice to a U.S. aviation group in its domestic, international and commercial business transactions.
  • Represents New Zealand fruit growers and healthcare clients in franchise arrangements in the U.S.
  • Acts as external general counsel to U.S. software engineering company that provides testing safety software to the U.S. government, foreign governments, auto manufacturers and others. 
  • Advises foreign companies involved in manufacturing, real estate, retail and other industries on structuring business operations in the U.S.
  • Provided cross-border tax advice to a premier provider of Internet network services and its acquisition of an Australian e-commerce company.
  • Represented several Washington municipalities and companies in state and local tax controversy matters.
  • Advised public Internet company on worldwide tax and licensing issues.
  • Represented a Canadian publicly-traded wine conglomerate with the acquisition and structured financing of the second largest wine producer in Washington state.

Professional Activities

  • Licensed U.S. Customs Broker
  • Past-President, Tax Section of the Washington State Bar Association, 2007-2008
  • Inter-Pacific Bar Association, Committee Coordinator; Past-Chair of the Tax Law Committee, 2005-2008
  • Former Tax Counsel, City of Seattle, Specializing in State and Local Taxation, 1990-1999
  • Canadian Tax Foundation, 2003-present
  • International Fiscal Association, Member of the United States and Canadian Branches, 2002-present
  • Canada-America Society, 2001-present

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  • Washington, 1983


University of Washington School of Law, LL.M., Taxation, 1999

Seattle University School of Law, J.D., 1983

University of Washington, B.A., cum laude, 1975

Honors | Recognitions

  • Named as one of The Best Lawyers in America© , Tax Law, 2011-2017
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