Margaret O'Sullivan is Managing Partner of O'Sullivan Estate Lawyers. Her practice involves all aspects of trust and estate work for domestic and international private clients, including estate planning; will and trust planning; incapacity planning; estate litigation; advising executors, trustees and beneficiaries and administration of estates and trusts, with a focus on high net worth domestic, cross border and multi-jurisdictional succession issues.

Margaret is recognized in The Best Lawyers in Canada 2018, Legal Week’s Private Client Global Elite 2018, in the 2018 Edition of The Canadian Legal Lexpert Directory as one of the most frequently recommended estate planning lawyers, in The Who’s Who Legal: Private Client 2018 and in The Who’s Who Legal: Canada 2018 as one of the five leading trust and estate lawyers in Canada. She is one of the six top-ranked private client lawyers 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 the firm’s trusts and estates practice. She has practiced exclusively in the area of trusts and estates since 1983.

Visit O’Sullivan Estate Lawyers website or contact Margaret at mosullivan@osullivanlaw.com. 

Articles

Estate planning risk when beneficiaries live abroad

By Margaret O'Sullivan (Published on 02-27-2026)

U.S. estate tax reform benefits Canadians

By Margaret O'Sullivan (Published on 01-27-2026)

Why we put off estate planning

By Margaret O'Sullivan (Published on 09-19-2025)

Lessons learned from the Murdoch Trust dispute

By Margaret O'Sullivan (Published on 07-29-2025)

What to expect for U.S. estate tax now

By Margaret O'Sullivan (Published on 02-11-2025)

Discretionary trusts in a marital breakdown

By Margaret O'Sullivan (Published on 10-01-2024)

Financial spring cleaning

By Margaret O'Sullivan (Published on 05-10-2024)

EU estate-planning uncertainty

By Margaret O'Sullivan (Published on 09-22-2023)

U.S. estate tax lifetime exclusion amount set to drop

By Margaret O'Sullivan (Published on 03-16-2023)

Multijurisdiction jigsaw puzzle: which law applies?

By Margaret O'Sullivan (Published on 09-27-2022)

Setting guidelines for personal care

By Margaret O'Sullivan (Published on 06-16-2022)

Cut tax with prescribed-rate loan strategy for trusts

By Margaret O'Sullivan (Published on 04-06-2022)

U.S. estate and gift tax turmoil

By Margaret O'Sullivan (Published on 02-10-2022)

Global push to raise wealth taxes

By Margaret O'Sullivan (Published on 02-03-2022)

How to choose a Power of Attorney for Personal Care

By Margaret O'Sullivan (Published on 12-07-2021)

The vital importance of integrity in estate planning

By Margaret O'Sullivan (Published on 09-15-2021)

Five essential rules for executors and trustees

By Margaret O'Sullivan (Published on 05-12-2021)

Cross-border estate-planning traps

By Margaret O'Sullivan (Published on 02-24-2021)

The year that propelled change

By Margaret O'Sullivan (Published on 12-24-2020)

Implications of a wealth tax in Canada

By Margaret O'Sullivan (Published on 11-26-2020)

Choosing the right executor for your will

By Margaret O'Sullivan (Published on 09-29-2020)

One tax too many

By Margaret O'Sullivan (Published on 08-13-2020)

Is Canada lagging on ‘Best Interest Standard’?

By Margaret O'Sullivan (Published on 05-26-2020)

The evolution to virtual execution of wills

By Margaret O'Sullivan (Published on 04-16-2020)

The fading need for death taxes

By Margaret O'Sullivan (Published on 02-27-2020)

How to create a family contingency plan

By Margaret O'Sullivan (Published on 01-16-2020)

Getting ready for new trust disclosure rules

By Margaret O'Sullivan (Published on 11-26-2019)

Succession planning: the common law/civil law divide

By Margaret O'Sullivan (Published on 10-22-2019)

Dealing with mental health issues in estate planning

By Margaret O'Sullivan (Published on 09-17-2019)

The art of transitioning wealth

By Margaret O'Sullivan (Published on 08-13-2019)

Update on Medical Assistance in Dying

By Margaret O'Sullivan (Published on 07-18-2019)

Canada’s tax rates among highest in the world

By Margaret O'Sullivan (Published on 05-30-2019)

Spousal property division on death not cut-and-dried

By Margaret O'Sullivan (Published on 02-26-2019)

Privacy: trusts become an open book

By Margaret O'Sullivan (Published on 12-27-2018)