Guillermo A Lalanne

Constitutional Tax Law, Tax Litigation & Tax Controversy, National, Provincial and Municipal Taxation, International Taxation, Tax Planning, Cross-Border Transactions

Guillermo A. Lalanne is a Partner in O'Farrell’s Tax Department and a leading practitioner in constitutional tax law, tax litigation and local taxation. He advises domestic and international clients on complex tax disputes, national, provincial and municipal taxes, cross-border transactions and strategic tax planning. Throughout his career, he has represented clients in landmark constitutional challenges and high-profile tax controversies, particularly those involving taxation in inflationary environments, municipal taxation and the interaction between constitutional principles and tax legislation. His practice combines extensive litigation experience with a strong academic background and active participation in the development of tax law in Argentina.

- Former President of the Argentine Association of Fiscal Studies (AAEF), the Argentine branch of the International Fiscal Association (IFA).

- Former Counselor, Treasurer and Secretary of the Argentine Association of Fiscal Studies (AAEF).

- Member of the Permanent Advisory Council of the Argentine Association of Fiscal Studies (AAEF).

- Former Professor of Tax Law, University of Navarra (Spain).

- Professor in postgraduate tax programs at Universidad Austral and Universidad Torcuato Di Tella.

Guillermo Lalanne frequently publishes articles and papers on constitutional tax law, tax controversy, local taxation and international tax matters in specialised journals and professional publications. He is a regular speaker at academic conferences, tax forums and professional associations in Argentina and abroad.

Professor of the Master’s Degree course in Tax Law at the Law School of Universidad Austral.

Professor of the Master’s Degree course in Tax Law at the Law School of Universidad Torcuato di Tella.

Professor of the Major in Tax Law Program at the Law School of Universidad Nacional de Córdoba.

Guillermo Lalanne advises domestic and international clients on constitutional tax law, tax litigation, local taxation and complex tax controversy matters. He is particularly recognised for his expertise in provincial and municipal taxation, tax inflation adjustment disputes, constitutional challenges to tax legislation, cross-border transactions and strategic tax planning. His practice includes representing clients before tax authorities, tax courts and judicial tribunals, as well as advising on the tax implications of corporate restructurings, international transactions and business operations in highly regulated industries.