William E. Keenen

William E. Keenen focuses his practice primarily on estate planning for high-net-worth and ultra-high-net-worth individuals and their families. He works with entrepreneurs, private equity fund principals and managers and other business owners and executives to pursue their multigenerational wealth transfer objectives. He routinely advises clients who are relocating from high-income-tax jurisdictions within the United States and has experience advising clients in the sports and entertainment sectors concerning their unique estate planning needs. In furtherance of his clients’ objectives, William prepares wills, trusts and a variety of other instruments and, where appropriate, designs more sophisticated estate planning structures.

William is often called upon by clients to assist them with the negotiation and preparation of a variety of marital agreements, including prenuptial and postnuptial agreements. In addition, family lawyers have sought William’s help in resolving complex trust matters arising in the context of divorce.

William counsels clients with respect to the day-to-day administration of trusts and estates, including in matters involving post-mortem tax planning. He has assisted individual and corporate fiduciaries, as well as beneficiaries, in litigated trust and probate matters.

William has represented clients in tax controversies and other tax compliance matters before the Internal Revenue Service (IRS), including matters of U.S. income, estate, gift and generation-skipping transfer (GST) taxation, and, early in his career, offshore voluntary disclosures. He has also assisted clients with the formation and operation of private foundations and with the negotiation and preparation of agreements implementing lifetime and testamentary gifts to non-profit institutions.

William has written about and lectured on various transfer tax topics affecting wealthy individuals and their families, including in the areas of shifting domicile within the United States, allocations of GST exemption and the application of the U.S. estate and gift tax law to transfers of property by citizens and non-citizens of the United States.

Concentrations

•Multigenerational wealth transfer planning
•Estate, gift and GST tax matters and controversies before the IRS
•International estate planning
•Prenuptial and postnuptial agreements
•Trust and estate administration and litigation
•Business succession planning
•Private foundations

Recognition & Leadership

Awards & Accolades

•Listed, The Best Lawyers in America
•Tax Law, 2025-2026
•Trusts and Estates, 2026
•'Ones to Watch,' Tax Law; Trusts and Estates, 2021-2024
•Listed, South Florida Legal Guide, 'Top Up-and-Comer,' 2020-2022