Mr. Calleja’s expertise covers all main taxes, with a strong focus on corporate taxation and transfer pricing; comprises all major industries (including telecom, energy, mobility, hospitality, technology, construction, retail, finance and private equity); and involves transactional work in Europe, Asia, the U.S., LATAM and North Africa. In addition to tax advice, he frequently coordinates and supervises relevant commercial law matters.

Mr. Calleja regularly acts as a trusted senior advisor to boards, Executive Directors and top management, addressing sensitive tax, legal, accounting and financial matters affecting listed corporations. He also brings wide experience in successfully conducting milestone tax controversy cases, high-level negotiations with governments and lobbying before regulators.

Prior to joining A&M, Mr. Calleja was with White & Case LLP, where he served as Head of Tax in Madrid. Previously, he served as a Partner with J&A Garrigues, SLP where, in addition to client work, he also assumed international management responsibilities.

Mr. Calleja is an officially Registered Accounts Auditor with the Spanish Ministry of Economy, an OECD-appointed Private Expert on Transfer Pricing and Business Restructuring, Member of the Spanish Institute of Managing Directors, Member of the Madrid Bar Association and Academic Director and Professor at the Garrigues Law and Business School’s International Business Law Master’s Program.

Mr. Calleja earned bachelor’s degrees in law and economics from Comillas Pontifical University (ICADE) and a master’s degree in the Spanish tax system from the School of Economics. He is also a graduate of the Harvard Business School Leading Professional Services Firms executive program. Consistently, he is featured for his tax expertise by independent international rankings, including Chambers, Euromoney, ITR, Who's Who and Best Lawyers.