Romain Dayan is a Partner and co-head of the Indirect Tax department. With nearly 20 years’ experience in international, multidisciplinary firms, he advises French and international companies on their strategic VAT and indirect tax issues. A primary contact for finance and tax functions, he supports them in complex, high-stakes environments, notably in the industrial, energy, transport, automotive, services and technology sectors.
Romain advises international groups on cross‑functional projects, both in advisory work and in tax audits and litigation. He works in particular on the structuring and VAT-related safeguarding of supply chains, the VAT analysis of complex cross‑border transactions, and the management of VAT deduction rights.
He also supports tax and finance teams in reviewing their internal VAT processes and in organising and transforming the tax function in connection with operational, financial and compliance requirements. Aware of the growing importance of formal requirements in indirect taxation, he assists companies with implementing the reliable audit trail (piste d’audit fiable) and electronic invoicing systems.
Before joining Grant Thornton Société d’Avocats in 2026, Romain worked at Ernst & Young Société d’Avocats from 2006, then at Fidal’s International Department in 2011, and at KPMG Avocats in 2019, where he developed deep expertise in indirect taxation and in coordinating international projects.
Since 2012 he has taught in the Master II in Business Tax Law at the University of Rennes, where he lectures on intra‑EU VAT, electronic invoicing and tax audits.
Redrafting and integration of French VAT legislation into the new CIBS code: implementation postponed to 1 January 2027
In a decision of 13 May 2026 (Stellantis Portugal, C-603/24), the CJEU ruled again on the connection between transfer pricing adjustments and VAT
