William Sharp is an attorney in Holland & Knight's Atlanta, Tampa and San Francisco offices (residing in Atlanta and San Francisco) with more than 35 years of experience representing clients in a wide variety of international tax planning and tax controversy cases. Mr. Sharp provides international and domestic tax advice to numerous U.S.-based and foreign-based clients, including publicly traded and closely held entities. His tax practice also focuses on globally oriented high-net-worth clients, including many U.S. and foreign-based family offices. Mr. Sharp has served as lead counsel with respect to U.S. Tax Court proceedings, Internal Revenue Service (IRS) appeals and examination cases. He also has served as lead counsel or co-counsel to more than 1,500 IRS voluntary disclosure cases.

Mr. Sharp advises financial institutions and their clients on international tax enforcement and compliance initiatives. In addition, Mr. Sharp represents several Swiss-based banking institutions in connection with the U.S. Department of Justice Swiss Bank Program, including the largest bank participating in the program and one of the major cantonal banks (both cases were resolved under Category 3 of the program). Mr. Sharp also has extensive experience in handling matters related to the Foreign Account Tax Compliance Act (FATCA) and other cross-border compliance and disclosure initiatives.

Mr. Sharp has served as an adjunct professor at the Stetson University College of Law and a lecturer at the University of South Florida Executive MBA program. He is a frequent speaker on international tax and business law matters. In addition, Mr. Sharp has been featured as well as quoted in publications such as the Wall Street Journal, The New York Times, The Washington Post, Reuters, USA Today and other media on international tax issues.

Prior to joining Holland & Knight, Mr. Sharp was founding and managing partner of a boutique international tax law firm with offices in Tampa, San Francisco, Washington, D.C., and Zurich, Switzerland.

Admitted in Florida only. Practice limited to federal tax matters.

Representative Experience

  • Advising on the establishment of a Swiss headquarters for a global nonprofit organization by way of a Swiss foundation with Swiss and non-Swiss special purpose investment entities that will launch and manage a global social impact investment program focusing on clean energy, water, housing and transportation, including working with Swiss tax counsel and structuring, negotiating and securing appropriate privileges, immunities and related benefits pursuant to Swiss tax‑free rulings under Swiss Federal and Swiss Cantonal law; once established, the global social impact investment program intends to sponsor a series of global social impact projects in the developing world, including a multibillion-dollar renewable $5 billion energy project in Mexico, an $8 billion infrastructure project in India, among others
  • Advising the U.S. tax structuring of a U.S.-exempt organization establishing an exempt charitable foundation counterpart under Swiss law to pursue non-U.S. charitable undertakings

  • Advising on the restructuring of a family office's U.S.-controlled European operation that involved several industries and implicating several hundreds of millions of dollars of revenue to be earned in the foreseeable future, with the focus of such tax advice on certain post-merger and acquisition (M&A) dispositions as well as certain other revenue-generating businesses, including collaboration among Luxembourg, Dutch and Swiss tax counsel
  • Advising a Florida-based $70 million fund that focuses on renewable energy throughout the Caribbean, Mexico and Central America
  • Advising several U.S.-based companies regarding the U.S. federal tax planning benefits of relocating residencies and businesses to Puerto Rico to take advantage of the special Puerto Rican Articles 20 and 22 low‑tax regime as respected by the U.S. federal government if certain conditions are met
  • Advising a long-time investment banking client regarding a new joint venture with Swiss-headquartered operation to focus on certain industry sectors
  • Advised a regional certified public accountant (CPA) firm regarding implications of deferred transition tax with respect to S-corporation proposed periodic dividends to underlying shareholders

  • Advised a European-based client with an annual turnover in excess of 8 billion euros with respect to certain reporting obligations under Foreign Account Tax Compliance Act (FATCA) as well as various pre‑residency U.S. income tax planning for key executive
  • Advising a Swiss-based family office owning several hundreds of millions of dollars in U.S. real estate with respect to restructuring alternatives resulting from U.S. tax reform
  • Advising a Swiss-based investment group with substantial U.S. real estate holding as to structuring cross-border compensation as well as advising on projected real estate sales to mitigate Foreign Investment in Real Property Tax Act of 1980 (FIRPTA) taxation
  • Advising on a pilot fund of $10 million from a foreign-based venture group to be utilized in the development of certain industry products in partnership with a U.S.-based executive team
  • Provided tax advice to a nonresident alien, who purchased a luxury real property in such a manner to mitigate U.S. estate tax risk, and at the same time become income tax neutral, and also began advising of pre-residency plan for relocating from Asia to the U.S. later in 2018

  • Advised on the proposed international $200-million joint venture of a U.S.-controlled global oil and gas client, and also advised on a cross-border sale to enable the affiliated group to separate active production operations from services and consulting; further advising such group with respect to deferral of transition tax as well as mitigating the global intangible low-taxed income (GILTI) exposure
  • Advising on a U.S.-controlled global energy client on a $236 million acquisition of a publically traded energy interests located in the Arab Republic of Egypt, and overseeing multi-country legal team
  • Advising a San Francisco-based tech company in connection with an acquisition of a United Kingdom‑based technology-oriented publication company, by way of a stock purchase agreement, including pre‑closing "checking the box" among other advisory points
  • Advising a Florida-based technology firm holding and operating industry-leading intellectual property on the structuring of an acquisition program designed to roll up several industry groups into an affiliated group for purposes of maximizing a third-party sale projected to be $225 million

  • Completing a multifaceted international succession plan on behalf of a high-net‑worth nonresident alien with respect to U.S. tax advice for structuring overall succession plan
  • Lead tax counsel in managing a global tax team with respect to advising a foreign-based client with a net worth in excess of $1 billion with respect to succession planning to both U.S.-resident and nonresident successors, including advise with respect to mitigating U.S. tax through various developed strategies over a one‑year term
  • Advising family office in restructuring 100 percent-focused domestic portfolio to carve off several billions of dollars of reinvest through a foreign-based legal structure, fully U.S. tax and foreign tax compliant, to diversify into foreign securities in various foreign-denominated securities as a part of the family office's succession plan

  • Provided a high-net-worth nonresident alien client with U.S. tax advice to complete unfreezing of client's Swiss bank account held with a Category 1 Swiss bank currently in negotiations with the U.S. Department of Justice (DOJ)
  • Serving as lead counsel to the largest Foreign Bank Account Report (FBAR) penalty case in the U.S. federal courts, prevailing in one of four years, and in the other three years prevailing on DOJ charges of willfulness; currently on appeal to the U.S. Court of Appeals for the Eleventh Circuit on various issues
  • Serving as lead counsel in U.S. Tax Court for legacy client regarding several tax issues, case settled at closing arguments after eight days of a virtual trial
  • Serving as lead coordinating counsel in pending arbitrations in Zimbabwe (settled February 2021) and London before the London Court of International Arbitration (pending); also served as review counsel for foreign-based legacy client in week-long arbitration in early 2021 (award pending)
  • Provided legal advice to resolve an almost three-year-old IRS examination involving a foreign parent corporation's U.S. subsidiary and indirect IRS review of several dozen other foreign affiliate entities, resulting in a relatively modest negotiated settlement amount, provided follow-on tax advice with respect to state tax authorities review of such case; the client is in the top five of its industry in the world
  • Lead counsel or co-counsel with respect to several pending U.S. Tax Court cases having significant international tax and related issues, including prevailing in the lead case in the U.S. Tax Court for defining bona fide U.S. Virgin Islands residency
  • Lead counsel in a U.S. District Court collection action filed by the DOJ to seek tax collection matter, and negotiated DOJ-approved settlement with respect to such tax assessments going back to the mid-1990s
  • Advising a Swiss-based bank as to the appropriate notification to the DOJ with respect to Category 2 (non-prosecution agreement) commitments under the Swiss Bank Program
  • Advising a the largest bank in Switzerland in terms of market share with respect to a DOJ update as required under 2016 Category 3 (non-target letter, no penalties) issued under the Swiss Bank Program with respect to DOJ inquiries
  • Advised (and continue to advise) on numerous Internal Revenue Service (IRS) examinations of Streamlined foreign clients selected for IRS review under such program
  • Advised on and completed a highly complicated foreign streamlined proceeding for U.S. citizen members of a prominent family owning and operating a global business with trading partners located all over the world
  • Advising on a post-closing agreement IRS analysis of Closing Agreement ramifications on certain material issues stemming from such Closing Agreement
  • Served as lead counsel to IRS "eggshell" examination following earlier case resolution of same fact pattern with the DOJ, and provided strategic and technical advice for satisfying IRS and successfully resolving such case with a "no change" finding
  • Providing cross-border tax advice with respect to an elderly U.S. citizen who also acquired citizenship abroad and who has a total estate in excess of $20 million but with respect to the foreign estate nothing has ever been declared in the United States, however, such holdings are in a high tax country where declarations have been made


  • New York University School of Law, LL.M., Taxation
  • Indiana University Robert H. McKinney School of Law, J.D., magna cum laude
  • Drake University, B.S., Accounting and Economics, with honors
Bar Admissions/Licenses
  • Florida
Court Admissions
  • U.S. Tax Court
  • U.S. Court of Appeals for the Eleventh Circuit
  • U.S. District Court for the Middle District of Florida
  • American Bar Association, Business Law Section, Section of Taxation, Section of International Law
  • Swiss-American Chamber of Commerce, Zurich
  • San Francisco Foreign Tax Club
  • International Fiscal Association
  • International Bar Association
  • Society of International Business Fellows (SIBF), Atlanta, 1985-Present; Chairman, 2001
  • The Carter Center, Board of Councilors, Atlanta
Honors & Awards
  • The Legal 500 USA, Tax – U.S. Taxes: Contentious, 2022-2024; Tax – U.S. Taxes: Non-Contentious, 2022; Tax – International Tax, 2023
  • The Best Lawyers in America guide, Tax Law, Litigation and Controversy - Tax, International Trade and Finance Law, 2005-2023; Lawyer of the Year, 2019
  • The Best Lawyers in America guide, Tampa International Trade and Finance Law Lawyer of the Year, 2021
  • Holland & Knight Pro Bono All-Star, 2021
  • ITR World Tax guide, Highly Regarded, Tax Leader, 2020
  • Chambers USA – America's Leading Business Lawyers guide, Tax, 2020-2024
  • Martindale Hubbell AV Preeminent Peer Review Rated
  • Florida Super Lawyers magazine, 2007-Present


Speaking Engagements