This guide explains who falls within the scope of the UAE Top-up Tax on Multinational Enterprises and how in-scope Entities register with the Federal Tax Authority. It covers the MNE Group and EUR 750 million consolidated revenue threshold conditions, including the rules for recently created Entities, Excluded Entities, short or long Fiscal Years, currency conversion, mergers and demergers. It defines the Entities in scope - Constituent Entities, Permanent Establishments, Joint Ventures, Flow-through and Hybrid Entities - sets out how an Entity and a Permanent Establishment are located, and details registration obligations, timelines, penalties and the application process, with worked examples throughout.