The team at O’Farrell is well versed in a broad range of tax matters, spanning tax inflation adjustment disputes, tax litigation before the Argentine Supreme Court, transfer pricing controversies and double tax treaty analysis in cross‑border transactions. The practice is headed by Miguel Tesón, who specialises in cross‑border transactions and corporate tax planning, and has recently been involved in disputes before the Argentine Federal Tax Authority and the Federal Court of Appeals, as well as leading high‑stakes constitutional tax litigation. Guillermo Lalanne focuses on national and local tax matters, frequently advising telecoms groups on tax inflation adjustment disputes, constitutional litigation and municipal tax controversies. María Celina Valls is particularly experienced in VAT and transfer pricing disputes, with notable work across the energy and agribusiness sectors. Semi‑senior associate Guadalupe Schettino is recognised for her contributions, and Florencia Shmunck, also a semi‑senior associate, joined the team from Rosso Alba & Rougès in June 2025.
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Testimonials
Collated independently by Legal 500 research team.
- Experience in litigating the same issues, technical expertise, and a willingness to answer questions.
- Availability, warmth, responsibility, efficiency.
- O'Farrell's team has extensive experience in tax law, particularly in inflation adjustments and transfer pricing. Celina Valls, in particular, stands out not only for her technical expertise but also for her results-oriented approach.
- Seriousness and responsibility in handling assignments.
- It is a long-established firm, deeply committed to its clients. It boasts highly qualified professionals who, in addition to their professional expertise, become personally involved in client defenses in tax-related cases, strengthening and focusing on building excellent evidence.
- In my opinion, the key is the close relationship with the client and the personal involvement of the partners in building defenses. Personally, I can give excellent references for María Celina Valls, Guillermo Lananne, and Miguel Tesón.
Key clients
- Pampa Energía
- Naturgy Argentina
- Droguería del Sud
- Ford Argentina
- S.A. Importadora y Exportadora de la Patagonia
- Grupo Telefónica Argentina
- Biogenesis Bago
- Transener
- Central Térmica Barragan
- SACDE
- Centro Diagnóstico Veterinario
- Telesistema
- Pilagá
- Adeco Agropecuaria
- Enaex Argentina
- Nortelevisa
- Vientos del Arauco Renovables
- Enaex Argentina
- Gasoducto del Pacífico
- El Hotel Pilar
Work highlights
Advised and represented Hidroeléctrica Los Nihuiles in a corporate income tax dispute, securing appellate and Supreme Court wins on both the depreciation of a hydroelectric concession and the application of tax inflation adjustment.
Advised and represented Pampa Cogeneración in a tax inflation adjustment case, securing a Federal Court of Appeals ruling that confirmed the full mechanism applied setting a concrete precedent on how partial inflation recognition can be challenged.
Advised and represented Telefónica Móviles Argentina in a high-stakes local tax dispute against the Municipality of Concordia.
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.
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 Lalanne; María Celina Valls; Guadalupe Schettino; Florencia Shmunck