A. William Caporizzo


Vice Chair, Transactional Department


Bill Caporizzo focuses his practice on the taxation of domestic and cross-border corporate mergers, acquisitions and dispositions, as well as international restructurings. His practice also includes the taxation of partnerships and limited liability companies engaged in investment activities and real estate activities. Learn more about Mr. Caporizzo's practice and how he can support your startup on

Mr. Caporizzo is a certified public accountant.

Honors & Awards

  • Recognized as a Massachusetts leader in the practice area of tax in the 2007-2017 editions of Chambers USA: America's Leading Lawyers for Business, with sources saying he is "really helpful in guiding the business people to understand the issues and to come up with solutions" and that "his advice is always tailored to the needs of the client"
  • Selected by peers for inclusion in the 2013-2018 editions of Best Lawyers in America for his tax law practice
  • Recommended in the 2016 and 2017 editions of the The Legal 500 United States in the area of Tax: US Taxes Non-Contentious
  • Recognized for exceptional standing in the legal community in the area of employee benefits in Chambers USA: America's Leading Lawyers for Business 2006
  • Named a "New England Super Lawyer" (formerly "Massachusetts Super Lawyer") in tax law in the 2004-2012 issues of Boston Magazine

Publications & News


March 8, 2018

New Partnership Audit Rules in Effect; Partnerships and LLCs Should Consider Changes

A new “centralized partnership audit regime” is now in effect for partnerships, including limited liability companies (LLCs) that are treated as partnerships for tax purposes (which we refer to collectively as “partnerships”). The new regime, which was enacted by the Bipartisan Budget Act of 2015, applies to all partnerships (domestic and foreign) for taxable years beginning after December 31, 2017.

February 8, 2018

WilmerHale Advises on the Formation of Valence Media, a New Diversified Media Company

WilmerHale served as legal counsel in connection with the creation of Valence Media, a new diversified media company formed through the combination of three successful media companies: Billboard-Hollywood Reporter Media Group, dick clark productions and MRC.

February 8, 2018

WilmerHale Represents Westmount Asset Management on Sale of Rosemont Stake to Temperance Partners

Westmount Asset Management, one of the oldest and largest independent investment firms in Los Angeles, has closed on the sale of Rosemont Investment Partners' stake in the firm to Temperance Partners.

January 25, 2018

WilmerHale Reps WorkMarket in Acquisition by ADP

On January 22, 2018, ADP® announced the acquisition of WorkMarket, a leading cloud-based workforce management solution provider that allows companies to build and manage an integrated workforce across W-2 employees, 1099 contractors, vendors and other types of workers.

January 23, 2018

WilmerHale Represents HS2 Solutions in Acquiring LunaMetrics

Digital transformation agency HS2 Solutions announced that it has completed the acquisition of LunaMetrics, an award-winning analytics consultancy that specializes in using data to help businesses illuminate the bridge between marketing, user behavior and ROI.

January 12, 2018

Tax Cuts and Jobs Act Summary

On December 22, 2017, President Trump signed sweeping tax reform legislation (H.R. 1) into law. The new law, commonly known as the Tax Cuts and Jobs Act, makes significant changes to the Internal Revenue Code that will have an impact on individuals, pass-through businesses, corporations, tax-exempt organizations, executive compensation and international taxation.

December 5, 2017

Astellas Acquires Mitobridge Under Existing Collaboration

Astellas Pharma Inc. and Mitobridge, Inc. announced that Astellas has exercised its exclusive option right to acquire Mitobridge under the amended terms of the October 2013 partnership agreement.

November 29, 2017

WilmerHale Represents Akamai in Acquisition of Nominum

Akamai Technologies, Inc. announced the company completed its acquisition of Nominum, a provider of DNS-based security solutions supporting many of the world's leading carriers.

October 19, 2017

WilmerHale Reps Cydan in Raising $34M to Accelerate New Treatments for Rare Genetic Diseases

Cydan, the first orphan drug accelerator dedicated to advancing therapies that improve the lives of patients with rare genetic diseases, announced a new round of financing, raising a committed total of $34 million to advance the company's efforts to create new and innovative therapies for patients living with rare genetic diseases.

October 6, 2017

WilmerHale Represents Navient in $155M Acquisition of Earnest

Navient, a leading provider of asset management and business processing solutions, announced it has entered into an agreement to acquire Earnest, a leading financial technology and education finance company.

Professional Activities

Mr. Caporizzo has presented at seminars on taxation for the NASDAQ, National Association of Stock Plan Professionals, and Massachusetts Continuing Legal Education Program. He is a member of the Tax Sections of the American and Massachusetts Bar Associations and the Boston Bar Association.


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JD, magna cum laude, Boston University School of Law, 1985

BS, magna cum laude, University of Pennsylvania, 1982

Bar Admissions



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