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HNW Guide
Individual Profile

Margaret O'Sullivan

O'Sullivan Estate Lawyers LLP - Toronto

Margaret O'Sullivan - O'Sullivan Estate Lawyers LLP
  • TD Bank Tower
  • Toronto, Ontario, Canada
  • M5K 1E7

Profile submitted by Margaret O'Sullivan

Practice Areas

Practises exclusively in estate planning; estate litigation; advising executors, trustees and beneficiaries; administration of trusts and estates.

Professional Memberships

Past Deputy Chair, Director and Member of Council for Society of Trust and Estate Practitioners (STEP) Worldwide. Past Chair of Professional Standards Committee of STEP Worldwide, past Deputy Chair of STEP (Canada), and past Chair of editorial board for STEP Inside. Member of STEP Cross Border Estates Global Steering Committee. Past Chair, Trusts and Estates Section, Ontario Bar Association (“OBA”). Academician of The International Academy of Estate and Trust Law. Fellow of American College of Trust and Estate Counsel. Member of Council, OBA (1993–98). Current member of the Canadian Bar Association, the American Bar Association, the New York State Bar Association, the International Bar Association, the Canadian Tax Foundation.


Margaret is recognized in The Best Lawyers in Canada 2019, in the 2018 Edition of the Canadian Legal Lexpert Directory as a most frequently recommended practitioner in estate planning, in the Who's Who Legal: Private Client 2018 and in The Who's Who Legal: Canada 2018 as one of the most highly regarded private client lawyers. She is ranked at the highest ranking of Band 1 in Chambers Canada Guide 2018 and in Chambers High Net Worth Guide 2018. She is the recipient of the 2014 STEP Founder’s Award for Outstanding Achievement and the Ontario Bar Association’s 2013 Award of Excellence in Trusts and Estates Law. Prior to establishing an independent practice, Margaret was a partner in the Toronto office of the national Canadian law firm Stikeman Elliott where she directed its trusts and estates practice. She has practiced exclusively in the area of trusts and estates since 1983.


Authored two textbooks, Engineering of a Trust and Trust and Estate Management, for Trust Institute, Institute of Canadian Bankers. Author, Canada chapter, International Succession Laws (Tottel 2009). Co-author, Canada chapter, The Private Wealth & Private Client Review (Law Business Research Ltd 2017). Contributing author to Widdifield on Executors and Trustees (Carswell 2002), The International Comparative Legal Guide to Private Client 2018 (Global Legal Group Ltd 2017), Practical Law Global Private Client Guide (Thomson Reuters) and Lexis Practice Advisor Canada (LexisNexis).


Called to Ontario Bar (1983).