Mario A. de Castro

About Mario A. de Castro

Mario is a business advisor and attorney with Buchanan’s Washington, D.C, office. He focuses on international and cross-border transactional corporate and tax matters. With over 20-years of experience, Mario serves large and middle-market (and closely held) multinational clients in myriad business sectors (including manufacturing and distribution, hospitality, technology and FinTech, private equity, professional and engineering services, and government contracting) operating in the U.S. and abroad. Mario\'s technical areas of experience and focus are: Cross-border U.S. and foreign transaction tax planning (including: market expansion,\"permanent establishment\" risk management, IP planning, M&A, due diligence, FIRPTA analysis, multilateral and treaty considerations, document review and preparation, opinion letter preparation and review, maintenance of existing corporate structures (management of NCTI, Subpart F Income, withholding taxes, etc.), intercompany transaction documentation, and tax and corporate compliance project review); tax and corporate information reporting compliance (e.g, 5471, 5472, FBAR, and related reporting review, FATCA, Corporate Transparency Act (CTA), BEA Survey Reporting, AML, and CFIUS Review); and in the closely held middle-market context, counsel U.S. and foreign family clients with cross-border private transaction and wealth transfer planning.

Experience

1. Shareholder

   Buchanan Ingersoll & Rooney PC

   Jan 2026 — Present · Washington, DC, US

Education

• University of Miami School of Law

  LL.M, Tax (International Tax Cert)

  2001 — 2003

• Christopher Columbus High School

  High School Degree

  1983 — 1986

• Tulane University

  BA, Political Science / International Relations

  1986 — 1990

• Temple University - James E. Beasley School of Law

  JD, Law

  1991 — 1994

Skills

• Tax Accounting
• Corporate Tax
• International Project Management
• Private Equity
• Hospitality Industry
• Direct Foreign Investment Advisory
• Corporate Governance
• Financial Transactions
• Auditing
• Income Tax
• Tax Law
• Corporate Law
• Tax
• Cross-Border Transactions
• Commercial Litigation
• Due Diligence
• Government Contracting
• Latin American Business
• International Tax
• Sarbanes-Oxley Act
• Estate Planning
• Tax Research
• International Tax Consulting
• International Law
• Europe, the Middle East, and Africa (Emea)
• International Business Law
• Restructuring
• Legal Writing
• Litigation
• Latin America Business
• Tax Advisory
• Transfer Pricing
• Indirect Taxation
• Technology Industry
• Mergers & Acquisitions
• Real Estate Transactions