Excellence.
Customized Solutions.
High-Touch Service.
For over 27 years, we’ve been distilling big-firm expertise and recreating it in a discreet, boutique firm setting.
Trust and Estate Legal Services
We established our firm over 27 years ago to focus 100% on trust and estate legal work
We provide domestic, cross-border and multijurisdictional trust and estate advice in a comfortable, discreet and personal boutique firm setting. From planning to administration to dispute resolution, our years of practical experience, combined with a deep understanding of your unique goals and objectives, enable us to provide bespoke solutions in a responsive manner that optimize your situation and ensure your peace of mind.
Celebrating Our 25th Anniversary
2023 marked the year O’Sullivan Estate Lawyers LLP celebrated its 25th anniversary. We thank our clients, professional colleagues, and “Friends of the Firm” for all of their support in contributing to this achievement and for the trust you place in us.
Estate Planning Lawyers, Estate Administration Lawyers for High Net Worth Individuals and High Value Estates
The estate planning lawyers and estate administration lawyers at O’Sullivan Law have pioneered 3 niche areas of trust and estate law for high net worth (HNW) individuals:
- Cross-border succession planning as well as estate and trust administration (Canada-U.S.)
- Multijurisdictional succession matters and estate administration (including situs wills and powers of attorney)
- Estate planning and administration for the Modern Family
Complex Estate Planning
Do you have a large or complex estate? The estate planning lawyers at O’Sullivan Estate Lawyers can also help with:
- Minimizing taxes on your death
- Protecting your children’s inheritance in the event of relationship breakdown
- Passing down or transferring special assets such as a business or cottage
Recognized Leaders in the Field
Our lawyers are not only legal practitioners but also leaders in our profession
All of us are active speakers and thought leaders. We are committed to staying at the forefront of the law and leading the charge.
We are also a top-ranked, peer-recognized firm. Margaret O’Sullivan is recognized by Chambers and Partners in the Canada High Net Worth Guide 2024 as a top estate planning lawyer in Canada.
Margaret O’Sullivan is recognized by The Best Lawyers in Canada 2025 and the Canadian Legal Lexpert Directory 2025 as a leading estate planning lawyer.
Margaret is recognized in Private Client Global Elite 2025.
O’Sullivan Estate Lawyers is ranked a “Top 10 Wills, Trusts and Estate Law Boutique” in Canada for 2023-2024, by Canadian Lawyer Magazine, part of Key Media. The survey is based on peer reviews by Canadian lawyers.
Margaret O’Sullivan won Bronze in the “Outstanding Individual of the Year” category in the Citywealth Powerwomen Awards USA 2024. She was the only Canadian nominated.
O’Sullivan Estate Lawyers was awarded Boutique Firm of the Year 2019/20 at the STEP Private Client Awards held in
London U.K. on September 25, 20195
Margaret O'Sullivan wins Bronze, in "Outstanding Individual of the Year" Category
Join us in congratulating Margaret O’Sullivan, founder and managing partner of O’Sullivan Estate Lawyers LLP, in winning Bronze in the “Outstanding Individual of the Year” category in the Citywealth Powerwomen Awards USA 2024.
Margaret responded on winning this award: “This is a special honour that means a lot to me. As the only Canadian nominated this year, I hope to help other Canadian women leaders who work with private clients and high net worth individuals in wealth management, to inspire the next generation.”
Mary Gardiner, of Morgan Stanley, won Silver and Sandra Viana, of Withersworldwide, won Gold in the “Outstanding Individual of the Year” category.
About Citywealth Powerwomen Awards
The awards shine a spotlight on individuals who are visionary leaders shaping wealth management and who go above and beyond in championing caregiving responsibilities, promoting female leadership, and embracing the power of diversity. Each finalist represented a story of inspiration and empowerment that deserves to be acknowledged.
A total of 20 Gold, Silver and Bronze Awards were announced. The winners were announced at an awards ceremony on March 14, 2024, in New York City.
In the Media
The Toronto estate lawyers at O’Sullivan Estate Lawyers are sought by reporters, editors, as well as TV and radio producers for their opinions and analysis of important estate issues, cross-border estate issues, trust and trust administration, as well as estate litigation.
“The O’Sullivan team has deep domestic, international and cross-border expertise, and their depth of trust and estate planning knowledge is close to unparalleled. I feel comfortable referring my clients because the nature of their advice is top-drawer. They are true experts.”
Read our 27th anniversary book “Trust and Estate Essentials: Achieving Success in Family Succession,” 3rd Edition. It will help clarify and demystify major issues that arise in estate planning and estate administration, especially high net worth Canadians with cross-border and multijurisdictional connections.
The 3rd Edition has been updated to 400 pages and divided into 48 germane chapters.
Available in hardcopy and eBook. Bulk orders welcome.
From Our Blog
1,270 Days Later: The Sequel to Substantial Compliance in Ontario
In November of 2023, I wrote about Ontario’s topical “validating” provision – section 21.1 of the Succession Law Reform Act (SLRA) – and whether it
Changing Your Mind and Your Family Trust Can Be Hard to Do: Just Ask Rupert Murdoch
Many of you may have read about the recent Murdoch family trust dispute, the elements of which are a real-life drama even more interesting than
Grant Me This: Resealing and Ancillary Probate Grants in Ontario for Multijurisdictional Estates
When a loved one passes away, one of the first legal steps in managing their estate can be the need for probate—the court process that
Conflict of Laws: An Interprovincial Perspective as to Which Laws Govern
If you have assets, prospective beneficiaries, or other connections to foreign countries, you have cross-border or multijurisdictional considerations in your estate planning or administration. Even
Contact Us to Discuss Your Needs
Our lawyers are ready to meet with you, listen to your needs and explain how we can help. Contact us to set up a meeting