William J. Kambas

Talks

• 'The Global Family Office: Challenges from Multijurisdictional Families,' 17th Annual STEP Los Angeles International Tax and Estate Planning Forum: 2025 Global Matrix - June 5, 2025, speaker

• 'U.S. and U.K. Current Developments,' 17th Annual STEP Los Angeles International Tax and Estate Planning Forum: 2025 Global Matrix - June 5, 2025, speaker

• 'Navigating Buy-Sell Agreements for Businesses,' Morgan Stanley 21st Century Single Family Office Symposium - November 6, 2024, speaker

• 'What is the corporate transparency act?,' The JWE virtual seminar - November 21, 2023, speaker

• 'International Commercial Real Estate Investment,' Withersworldwide webinar - October 11, 2023, co-presenter

• 'Tax Considerations for U.S. Inbound Business Activities,' USA Branch of the International Fiscal Association, Westchester/CT Regional Event - October 12, 2023, moderator

• 'How is family wealth owned and governed?,' Columbia Business School, Family Enterprise and Wealth, September 19, 2022, visiting lecture

• 'The Role of the Family Office for UNHW Families,' 14th Annual STEP Los Angeles International Trust and Estate Planning Forum - May 6, 2022, co-presenter

• 'Global Families in Flux,' 14th Annual STEP Los Angeles International Trust and Estate Planning Forum - May 5, 2022, co-presenter

• '5 Best Practices for World-Class Family Offices,' Family Office Association - April 5, 2022, interview

• 'A US Tax Lawyer's Perspective on EU Tax Havens,' Yale University, the Euro Crisis (Political Science, Sociology, and Modern Greek Studies) Spring Semester - March 17, 2022, visiting lecture

• 'Wine Calling: Strategies for investing in US wineries,' Withers presentation for select Italian clients - January 27, 2022, co-presenter

• 'Supporting the Family Enterprise: Pre-emptive Planning to Address Threats to the Family Ecosystem,' Family First Institute (FFI) Global Conference 2021 - October 18, 2021, co-presenter

• 'Who Should Own and Operate a Family Office and Ideal Structures,' Tamarind Learning Podcast Series - November 10, 2020, speaker

• 'Family Office Set-up, Structure, and Compliance,' Tamarind Learning Podcast Series - November 9, 2020, speaker

• 'Operating the Family Limited Partnership,' ABA Section of Real Property, Trust and Estate Law webinar, October 27, 2020, co-presenter

• 'Trust & Estate Law webinar: Operating the Family Limited Partnership,' webinar to ABA Section of Real Property - October 27, 2020, co-presenter

• 'Checklist 2020: Income tax planning for any outcome,' Withersworldwide webinar - October 21, 2020, co-presenter

• 'Family Office Summit: Structuring a New Family Office in the US and Challenges in Advising Existing Multinational Families,' webinar to STEP NY - October 20, 2020, co-presenter

• 'Withers talks: families and family office | Ep 1 - Structuring family offices for tax and investment benefits,' Withersworldwide podcast - August 27, 2020, speaker

• 'Family Governance: Generational Continuity through Risk Mitigation, ABA Section of Real Property,' Trust & Estate Law's 32nd Annual CLE Conference - May 14, 2020, co-presenter

• 'Tax and Estate Planning for the Family Business,' Columbia University Business School, Family Business Management - April 20, 2020, visiting lecture

• 'Planning for Investment into the United States,' __ ALI CLE International Trust and Estate Planning 2019, Washington, D.C. - November 15, 2019, panelist

• 'Planning for the Business Owner: U.S. Clients Who Own Non-U.S. Business Interests,' ALI CLE International Trust and Estate Planning 2019, Washington, D.C. - November 15, 2019, panelist

• 'Cross-Border Case Study,' STEP Wyoming International Estate Planning Conference - September 21, 2019, co-presenter

• 'Avoiding Fiduciary Litigation in the Age of Technological and Digital Transformation,' Robins Kaplan LLP Wealth Planning, Administration, and Disputes Group, The Future of the Fiduciary - September 12, 2019, panelist

• 'Family Forum - Stories from the Front Lines: Dynamic Estates,' New York State Bar Association, Family Governance Symposium - July 15, 2019, co-presenter

• 'Essentials of Family Offices for the Estate Planner - A Primer on Functions, Structures, and Related Issues' at the 53rd Annual Heckerling Institute on Estate Planning by the University of Miami School of Law - January 17, 2019, co-presenter

• ‘Planning the Estate: Multijurisdictional Estate Planning with a Family Business,' Columbia University Business School, Family Business Management - November 13, 2018, visiting lecture

• 'Family Office Operations 2018: New Ideas and the Evolving Landscape of Taxation,' Citi Private Bank - May 3, 2018, co-presenter

• 'Tax reform and the family office', Withers New York and Greenwich event - June 2018, speaker

• '5th Annual Family Business School Conference-Family Office Panel,' Columbia Business School - February 9, 2018, moderator

• 'US Tax Reform,' STEP Canada/STEP USA Webcast - January 19, 2018, panelist

• 'Interactive round table discussion', STEP International Estate Planning Conference Wyoming - September 15-16, 2017, moderator

• 'Greek Family Firms: Exploring the Logic and Dynamics of the International Shipping Enterprise' Yale University, The MacMillan Center, Hellenic Studies Program, with Elian Kulukundis, May 2017

• 'Encouraging Engaged Ownership through Legal Architecture,' International Association of Attorneys for Family-Held Enterprises ("AFHE"), Miami, FL, April 27. 2017

External publications

• 'Succession & Estate Planning 2026: USA - Connecticut,' Chambers and Partners - March 25, 2026, co-authored

• 'Family Office Investment in US Sports: Combining Financial Returns with Social Engagement,' FFI Practitioner - March 4, 2026, co-authored

• 'Bridging international risk management for entities in the family enterprise,' FFI Practitioner - September 17, 2025, co-authored

• 'From sidelines to bottom lines: How the One Big Beautiful Bill Act hits the sports industry,' Withers Insight - August 4, 2025, co-authored

• 'One key consideration: Family office and private clients get a gift from the OBBBA,' Withers Insight - August 1, 2025, authored

• 'How the New Tax Law Benefits the Wealthy,' Barron's - July 16, 2025, quoted

• 'Do International Concerns Factor Into Your Estate Plan?,' Greenwich Time - June 28, 2025, quoted

• 'The Family Bank: Some Legal and Fiduciary Perspectives on Deploying Financial Capital,' FFI Practitioner - June 18, 2025, co-authored

• 'Family Offices Escape Beneficial Ownership Requirements Under the US CTA,' Family Capital - March 25, 2025, quoted

• 'Family Constitutions to Guide Founders, Owners, Families, and Advisors,' FFI Practitioner - March 18, 2025, co-authored

• 'Treasury Announces Shift in CTA Focus to Foreign Companies,' Tax Notes - March 4, 2025, quoted

• 'These Rich Investors Fly Under the Radar. Trump Could Keep It That Way,' Barron's - February 25, 2025, quoted

• 'Corporate Transparency Deadline Set, but Uncertainty Still Looms,' Bloomberg Law - February 20, 2025, quoted

• 'Trends in the Family Office Space: A Taw Lawyer's Perspective,' Financial Advisor - January 10, 2025, quoted

• 'The CTA, Chaos, and the Frustration of Family Offices,' Family Capital - January 7, 2025, quoted

• 'BOI Reporting in Flux Following Fifth Circuit Rulings,' Insightful Accountant - January 3, 2025, quoted

• 'Fifth Circuit Puts Corporate Transparency Act Back on Hold,' Tax Notes - December 27, 2024, quoted

• 'Appeals Court Reinstates Injunction on Beneficial Ownership Reporting,' Accounting Today - December 27, 2024, quoted

• 'Are Your Clients Ready to Comply with the Corporate Transparency Act?,' WealthManagement.com - November 27, 2024, co-author

• 'Family Office Compensation Considerations: An Introduction to the Lawyer's Perspective on Incentivizing and Compensating Key Leadership of a Family Office,' FFI Practitioner - November 5, 2024, co-author

• 'Welcome New Advisory Board Member, William (Bill) Kambas,' The UHNW Institute - September 26, 2024, recognized

• 'The World's Top Family Enterprise Advisors,'  Family Capital - July 30, 2024, recognized

• 'Family Offices Risk Future Without Investment Policy Statements,' Family Capital - April 30, 2024, quoted

• 'Generational resilience through the integration of governance into structure,' Essential Reads on Family Offices - December 2023, co-author

• 'Family Capital's 100 Influencers - Lawyers,' Family Capital - January 12, 2023, recognized

• 'Lacking structure, family offices fail to hire the right advisers,' Family Capital - November 8, 2022, quoted

• 'Family offices prepare for a federal register of beneficial ownership in the US,' Family Capital - November 3, 2022, quoted

• 'Family offices face regulatory hurdle with new transparency act,' Family Capital - February 8, 2022, quoted

• '3 Things Tax Pros Should Know About House's SALT Plan,' Law360 Pulse - November 24, 2021, quoted

• 'How the $1.75 trillion Build Back Better plan could impact Americans' taxes,' CNBC - November 24, 2021, quoted

• 'The best US and East Coast tax and trust lawyers for high net worth individuals,' Spears - September 29, 2021, featured

• 'Here Are the 21 People to Know When Starting a Family Office,' Business Insider - July 13, 2021, quoted

• 'Mexican legislative elections and the future of the tax reform,' Withers Insight - July 1, 2021, co-author

• 'Biden, tax, and how family offices will allocate their wealth,' Family Capital - April 27, 2020, quoted

• ‘Private client considerations: Understanding the impact of carried interest regulations on US family partnerships and family offices,' Withers Insight - March 16, 2021, co-author

• 'The Focus of the IRS Global High-Wealth Group,' Tax Notes - March 1, 2021, co-author

• 'Carried interest in 2021: New guidance for tax on income associated with services provided to investment partnerships,' Withers Insight - January 12, 2021, co-author

• 'The Corporate Transparency Act: A new US federal reporting requirement for beneficial owners of US entities,' Withers Insight - January 4, 2021, co-author

• 'State Tax Incentives Face Increased Scrutiny Amid COVID-19,' Law360 Tax Authority - October 30, 2020, quoted

• "'There's a Lot of Money To Be Made;" IRS Targets Foreign Real Estate Investors,' The Real Deal - October 16, 2020, quoted

• 'Generational resilience through the integration of governance into structure,' The International Family Offices Journal, 17th ed. Published by Globe Law and Business Ltd. - October 1, 2020, co-author

• 'The window for "easy" partnership amended returns for CARES Act benefits is closing,' Withers Insight - September 24, 2020, co-author

• 'IRS targets tax compliance by non-U.S. owners of U.S. real estate,' Withers Insight - September 24, 2020, co-author

• 'It takes a village, again: Applying a modern legal perspective with a view to enhancing resilience in family enterprises,'_ STEP Journal Volume 28 Issue 4 - August 28, 2020, co-author

• 'State CARES Act Decoupling Limits Benefits, Adds Complexity,' Law360 - July 31, 2020, quoted

• 'STEP NY IRS Comment Letter,' STEP NY - July 13, 2020, co-author

• 'An opportunity for U.S. real estate investors: Lower fair market values in 2020 might offer new opportunities for reorganization of holding structures,' Withers Insight - June 4, 2020, co-author

• 'No, You Can't Deduct A Home Office,' Barron's - May 9, 2020, quoted

• 'Private client considerations: CARES Act expands taxpayers' ability to utilize net operating losses and excess business losses,' Withers Insight - April 16, 2020, co-author

• 'Private client considerations: Expanded tax deductions for your interest expense payments with the CARES Act,' Insight - April 8, 2020, co-author

• 'Private client considerations: Benefits to small businesses from the CARES Act,' Withers Insight - April 6, 2020, co-author

• 'Alternative investments should be reviewed to address coronavirus related issues,' Withers Insight - March 31, 2020, co-author

• 'US federal and state income tax compliance adjustments in the wake of the coronavirus pandemic,' Withers Insight - March 30, 2020, co-author

• 'Tiered Structures for Family Office Operations: Integrating a Private Trust Company with a Family Office,' Probate & Property: An ABA Publication - September/October 2019, co-author

• 'Income Taxation of Trusts in the US: Stay Tuned for Controversy,' Trust Quarterly Review (a STEP publication) - September 2019, co-author

• 'How Wealth Accumulators Can Use Trusts To Avoid State Income Tax,' __ Forbes - July 22, 2019, quoted

• 'Global Law Firm Withers' Family Office Group Advises Ultra-Rich,' __ Bloomberg Law - June 25, 2019, featured

• 'Supreme Court finds North Carolina can't tax trust income,' Tax Notes - June 24, 2019, quoted

• 'Estate Planning for Owners of Closely Held Business Interests,' Tax Management Portfolio No. 809-4^th - May 2019, cited

• 'NC Trust Tax Row Could Fundamentally Alter Due Process Law,' Law360 Tax Authority - April 18, 2019, quoted

• 'North Carolina's position on trust questioned,' Tax Notes - April 17, 2019, quoted

• 'Supreme Court hears arguments on major state trust tax case,' Accounting Today - April 17, 2019, quoted

• 'Essentials of Family Offices for the Estate Planner - A Primer on Functions, Structures, and Related Issues,' University of Miami Heckerling Institute on Estate Planning - January 2019, co-author

• 'Post-Wayfair State Developments to Watch in 2019,' Law360 - January 1, 2019, quoted

• 'Can You Get an Income Tax Break if You Own Multiple Homes in the US?' Mansion Global - September 20, 2018, quoted

• 'Family Offices: Business, Not Personal,' Wealthmanagement.com - June 11, 2018, quoted

• 'S Corporations vs. C Corporations In 2018,' TaxConnections - May 24, 2018, quoted

• 'How 40 ambiguities (and outright errors) in the new tax law could cost you big money,' Inc.com - March 13, 2018, quoted

• 'The "new" alternative minimum tax,' Withers article - February 13, 2018, co-author

• 'Single family office operations 2018: Recent case law and coordination with legislative developments,' __ Withers article - February 12, 2018, co-author

• 'An obscure court case that will have a big affect on family offices,' Family Capital - February 8, 2018, quoted

• 'How the new federal and New York estate tax exemption could affect your estate plan,' Withers article - January 2018, co-author

• 'How the new federal and Connecticut estate and gift tax exemption could affect your estate plan,' Withers article - January 2018, co-author

• 'Why the US tax reforms are a headache for family offices,' Family Capital - January 30, 2018, quoted

• 'US tax reform - Single family offices and considerations for 2018,' - January 17, 2018, co-author

• 'How the tax code rewrite favors real estate over art,' The New York Times - January 12, 2018, quoted

• 'Tax changes affecting major real estate markets in the USA,' Withersworldwide.com - January, 2018, co-author

• '15 tips for year-end planning in light of the GOP tax bill,' Withersworldwide.com - December 21, 2017, co-author

• 'Top federal tax regulations of 2017: Year-in-review,' Law 360 - December 18, 2017 , quoted

• 'Effect of proposed US tax bill on family offices and investment vehicles,' Global Tax Weekly - November 30, 2017, co-author

• 'Update: Effect of proposed US House and Senate tax bills on family offices and investment vehicles,' - November 22, 2017, co-author

• 'New Year's resolutions - Revising partnership agreements as new audit rules take effect January 1, 2018,' Withersworldwide.com - November 22, 2017, co-author

• 'US Inbound Taxation: Senate Finance Committee tax reform plan would overturn recent Tax Court decision,' Withersworldwide.com - November 10, 2017, co-author

• 'Effect of proposed US tax bill on family offices and investment vehicles,' Withersworldwide.com - November 7, 2017, co-author

• 'Art market may lose 'driving force' as tax plan targets loophole,' Bloomberg Quint - November 3, 2017, quoted

• 'GOP Aims to Kill the Estate Tax: What it Means for You,' Fox Business Network - November 3, 2017, quoted

• 'Connecticut Legislature passes Budget Bill (Senate Bill 1502)', Withersworldwide.com - October 30, 2017, co-author

• 'Richest Americans doubt they'll really win in Trump's tax plan,' Bloomberg Politics - September 29, 2017, quoted

• 'Tax Court holds that non-US persons are not subject to tax on gain from the sale of a US partnership interest which is engaged in a US business under certain circumstances', Withers article, August 2017, co-author

• 'How U.S. Persons Can Be Made Public by the UK Register,' Estate Planning - August 2017, co-author

• 'New York Banking Royalty's Heirs Are Unloading Art to Save the Family Estate,' Bloomberg, April 2017, quote

• 'A Mediterranean comparison: Responding to the next steps in the implementation ofFATCA and global data exchange,' Investment - October 2015, author

Admissions

• State of Connecticut, 2003

• State of New York, 2004

• United States Tax Court, 2004

• State of Wyoming, 2019

Education

• Skidmore College, B.A.

• University of Connecticut School of Business, M.B.A.

• University of Connecticut School of Law, J.D. (Certificate in Tax)

Languages

• English

Memberships

• The Ultra High Net Worth ("UHNW") Institute, Advisory Board

• American College of Tax Counsel ("ACTC"), Fellow

• Society of Trust and Estate Practitioners "STEP" (New York), Member

• International Fiscal Association (Westchester, NY and Connecticut Region), Executive Committee

• Skidmore College Annual Fund, Past-President

• Saint Barbara Greek Orthodox Church Endowment Fund, Chairman

• Hellenic Bar Association of Connecticut

• New York State Bar Association

• Connecticut Bar Association

• American Bar Association

Key dates

• Year joined: 2006
• Year became partner: 2014