
O'Farrell‘s tax department offers a comprehensive practice and has a proven track record in tax litigation, achieving success for its clients in landmark tax cases before local, regional and national courts. The practice is well versed on a broad spectrum of tax related matters such as energy taxation, stamp tax, transfer pricing disputes and tax-free reorganisations among many others. The practice is led by Miguel A.M. Tesón, who has extensive experience representing clients in complex tax litigation before tax authorities on a municipal, provincial and national level. Guillermo Lalanne focuses on constitutional tax law and María Celina Valls handles transfer pricing disputes and issues related to inflation adjustment tax practice. The team was further strengthened with the arrivals of associates Ruben Velazquez in October 2024 and Daniel A. Calzetta in December 2024.
Legal 500 Editorial commentary
Testimonials
Collated independently by Legal 500 research team.
- ‘We are a medium-sized company and rely heavily on external advisors. We work with O Farrell on important matters because we know their track record and expertise. They are very approachable, have excellent relationships with people, and are flexible with invoicing.'
- 'Conceptual solid, practical experience, and thorough analysis and presentation of the case.'
Key clients
- Pampa Energía / Petrobras Naturgy Argentina
- Droguería Del Sud
Lawyers
Hall of Fame
The lawyers at the very top of the profession, widely known and respected by peers and clients for their longstanding involvement in market-leading work.

Leading partners
The strongest partners in their field, leading on market-leading deals and endorsed by peers and clients alike.
Valeria Estathio

Guillermo Lalanne
Next Generation Partners
Junior partners with significant recognition from clients and peers in the market and key roles on multiple matters.
Practice head
Miguel Tesón
Other key lawyers
Guillermo A. Lalanne; María Celina Valls; Ruben Velazquez; Daniel A. Calzetta

