Bill Mahaffey's practice focus is in the taxation, finance, corporate, and transactional areas. He has provided ‎counsel on a wide range of tax-sensitive matters.‎

More About H. William Mahaffey


  • LL.M., New York University School of Law, 1981
  • J.D., with honors, Brigham Young University, J. Reuben Clark Law School, 1980
  • B.A., Colorado State University, 1977

Bar Admissions

  • Colorado, 1982

Court Admissions

  • Colorado State Judicial District Courts
  • Colorado Supreme Court
  • Colorado Court of Appeals
  • U.S. Tax Court
  • U.S. District Court, District of Colorado


  • American Housing Program Subcommittee, Member
  • American Bar Association, Member
  • Colorado Bar Association, Member

Representative Matters

  • Nonprofit organizations, including initial exemption determinations, joint ventures with for-profit organizations, unrelated business income, and various operations and employee benefit matters. Bill has developed particular emphasis in tax-exempt financing for exempt organizations, charter school financing, and the financing of low- and moderate-income housing programs offered by tax-exempt organizations.
  • Mergers, acquisitions (taxable and tax-deferred), and reorganizations.
  • Banking regulatory and finance issues, including financial accounting aspects associated with financial institution regulatory capitalization requirements. 
  • Corporate taxation, partnerships, and limited liability companies, including formation and operational issues. 
  • Compensation and fringe benefit matters, including qualified and nonqualified options, self-funded welfare benefit plans, and related matters 
  • ERISA-related matters, including leveraged and non-leveraged ESOPs, qualified plans, and advice to plan sponsors concerning fiduciary and plan administration issues.
  • Estate and gift taxation planning. 
  • Assists in litigation in the Federal Tax Court and employee benefits litigation brought or maintained by plan participants or beneficiaries.

Honors & Recognitions

  • The Best Lawyers in America, Tax Law, 2016-2024
  • Chambers USA, Corporate/M&A, 2016


  • Beyond Wayfair: Implications For State and Foreign Taxes
    Quoted, 10/22/2018

Blog Posts


Bill regularly presents at a variety of professional speaking engagements. In the last year, he has made seminar presentations to lawyers and professionals on the following matters:

  • Partnerships, limited liability companies, and limited liability partnerships 
  • Charitable organization taxation-unrelated business income taxation 
  • Charitable organization taxation-employee fringe benefit planning (including qualified plans, 403(b) plans, and 457 plans)
  • Federal income tax aspects of divorce 
  • State sales and use tax, including taxation of interstate transactions
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