Article 13 mandates that all entities subject to Top-up Tax and Domestic Designated Filing Entities must register with the Federal Tax Authority (FTA). The FTA reserves the right to register entities at its discretion based on available information. Furthermore, entities must apply for deregistration if they cease to exist or fall out of the scope of the Decision. This article ensures a formal registry of in-scope MNEs is maintained for administrative and enforcement purposes under the Pillar Two framework.