William Kastin, P.C., Partner at our Phoenix law office
William Kastin, P.C. vcard
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William Kastin, P.C.

Partner
Biography

Bill Kastin’s practice concentrates on problem solving and comprehensive planning for individuals, corporations (including S corporations), partnerships, and limited liability companies (LLCs). He works with the client’s leadership team to identify, create, and help implement strategies that achieve the desired results in an efficient manner while being respectful of the client’s business culture.

Bill’s experience includes advising clients on business and joint venture formations, mergers & acquisitions, real estate transactions (e.g., dealer/investor issues), §1031 “like-kind” exchanges, condemnations, loan workouts and modifications for both debtors and creditors, private equity transactions, and daily operations. Bill has assisted with the drafting and submission of comments to Proposed Treasury Regulations so that the client’s concerns were adequately addressed in Final Treasury Regulations. He also advises the firm’s non-U.S. clients on the U.S. tax implications of their U.S. investments (inbound transactions), and the firm’s U.S. clients on the U.S. tax implications of their foreign investments (outbound transactions). Bill is rated as AV® Preeminent, the highest rating given by Martindale-Hubbell® Peer Review Ratings system.

Credentials

Bar Admissions

  • Arizona
  • New Jersey
  • New York


Court Admissions

  • Supreme Court of Arizona
  • Supreme Court of New Jersey
  • Supreme Court of New York


Education

  • New York University School of Law (LL.M., Tax)
  • Hofstra University School of Law (J.D.)
    • Hofstra University Labor Law Journal, Notes & Comments Editor
  • George Washington University (B.B.A.)
Experience

Awards & Recognition

  • Phoenix Magazine, Top Lawyers (2025)
  • The Best Lawyers in America®
    • Mergers and Acquisitions Law (2021-2026)
    • Tax Law (2022-2026)
    • Business Organizations (including LLCs and Partnerships) (2025-2026)
  • Chambers USA: America’s Leading Lawyers for Business®, Tax, Band 1 (2023-2025)

Professional Memberships and Activities

  • State Bar of Arizona
    • Tax Section
  • Maricopa County Bar Association
    • President (2014)
    • Board of Directors (2007-2015)
    • Real Estate Law Section
      • Founding Chair (2007-2009)
    • Corporate Counsel Division
      • Board Liaison (2007-2015)
  • American Bar Association Section of Taxation
    • Committee on Partnerships & LLCs
    • Committee on Real Estate
    • Committee on Sales, Exchange & Basis
  • U.S.-Mexico Bar Association

Representative Presentations and Publications

Client News
Client News
Sep 30, 2025

Snell & Wilmer Advises Clywedog Therapeutics in Proposed Merger with Barinthus Biotherapeutics

Client News
Sep 04, 2025

Snell & Wilmer Advises AVI-SPL on Acquisition of CCS Southwest

Client News
Jul 28, 2025

Snell & Wilmer Represents SocialPilot in Acquisition by Group.one

Client News
Mar 28, 2025

Snell & Wilmer Advises Lomond Therapeutics in $20M Private Investment Financing and Addition of Two New Investors