About Us

We are a boutique law firm specialising in tax, superannuation, trusts, structuring, estate planning, litigation & disputes.

Our clients are business owners, individuals and family groups and their advisers such as accountants.

Our services include taxation advice, business structuring, powers of attorney, wills and probate, superannuation and trusts and litigation and disputes related to each of these fields.

We are unique in that we have extensive experience across all of these areas of the law. This enables us to implement strategies and structures to help clients to protect their assets and implement tax effective personal and business succession solutions, often across generations.

We pride ourselves in offering practical advice in plain-English with transparent fee structures.

Meet the Team

Bernie O’Sullivan


  • One of Australia’s leading estate planning lawyers
  • Trusted confidant for family groups and high-profile clients
Bernie advises individuals and businesses on all aspects of wealth succession.  He acts as adviser to several prominent families, helping them manage their structures to meet their long term family wealth goals.  Bernie is particularly experienced in dealing with succession issues for entities such as family trusts and superannuation funds and providing solutions for complex family arrangements (such as blended families and vulnerable beneficiaries), international assets and charitable gifting. Bernie is the lead author of the acclaimed publication Estate and Business Succession Planning, published by The Tax Institute, now in its 7th edition.  He lectures for several universities and education institutions including Kaplan and is a regular presenter to accountants and financial advisers.

Professional Biography

Rob Warnock


  • Accountants go-to lawyer for taxation advice
  • Over 30 years’ experience representing taxpayers in ATO disputes
Rob advises accountants, businesses and individuals on tax related matters. He has more than 30 years’ tax experience and has also represented professional associations and taxpayers on ATO and Treasury tax consultation committees. Rob works closely with accountants and their clients helping them to obtain the best possible tax outcome. He looks for practical and innovative solutions and often has helped save tax for his clients using ideas from ‘left field’. Rob has a particular interest in trusts, tax planning, business restructuring and tax disputes. Rob advises on both Federal and State taxes including income tax, CGT, GST, stamp duty and payroll tax. He is a sought after speaker due to his clear and easy to understand style and has written and presented many papers at conferences. Rob is currently on the Victorian State Council of The Tax Institute.

Professional Biography

Patrick Cussen


  • Highly regarded tax and business lawyer
  • Advises on business acquisition and sales, succession and international structures
Patrick has almost 30 years’ experience advising accountants, businesses and individuals on tax related matters. He particularly focuses on advising accountants and their clients about structuring business and investment activities. Patrick advises on Federal taxes and related areas (including income tax, capital gains tax, fringe benefits tax, superannuation and GST), and State taxes and related areas (including duties, land tax, WorkCover and payroll tax). In addition to providing advice about tax matters, Patrick has experience in drafting the documents to implement the advice.

Professional Biography

Tim Colcutt

Senior Associate

  • Extensive litigation experience in estate, business and corporate matters
  • Trusted advisor who puts clients in the strongest possible position
Tim has extensive litigation experience in a range of areas including estates and trusts, corporate disputes, bankruptcy and corporate insolvency.

He regularly advises and represents executors, trustees and beneficiaries in relation to inter vivos and testamentary trusts and deceased estates, as well as business owners, directors and shareholders of private and public companies with respect to a range of business, ATO and banking disputes.

Tim’s broad legal experience enables him to help clients adopt prudent positions and strategies ahead of future transactions. This approach has led to Tim becoming a trusted advisor of his long-term clients.

Tim’s usual approach is to resolve disputes discretely and promptly but is always ready to vigorously litigate and defend clients’ positions where required.

Caitlin Coyne


Caitlin is an experienced lawyer who works predominantly in estate planning matters including the preparation of comprehensive Wills, powers of attorney and wealth succession of family trusts and self managed superannuation funds. Caitlin aims to provide practical legal advice and positive solutions for clients wishing to build and preserve generational wealth for their families, along with maintaining strong working relationships with accountants and financial planners. She is a member of the Law Institute of Victoria and the LIV Young Lawyers.

Prue Thwaites

Practice Manager

Prue manages the administrative functions of Bernie O’Sullivan Lawyers which include involvement in systems, accounting, human resources and marketing. Having worked in management and finance roles in a number of city law firms, Prue is familiar with the requirements of professional service firms. Enjoying an interest in the environment and travelling in remote areas of Victoria and Australia keeps Prue busy in her spare time.