Lack of interoperability is increasingly becoming a significant issue in the electricity sector. The need to integrate a growing amount of distributed resources, such as renewable energy sources and electric vehicles, means that interoperable energy services will play an increasingly vital role in maintaining the stability of the electricity system and enabling consumers to benefit from the energy transition. Much has been done to create a regulatory framework that can support the development of these new services and the related flexibility markets. However, the journey towards a completely digitalised electricity system which operates in a seamless way is still long. In light of this, this deliverable aims to provide policymakers and regulators with a series of considerations that may prove relevant when deciding how to improve the current regulatory framework. To develop these considerations, the main barriers to the development of interoperable energy services were identified through two main activities: a stakeholder analysis and an analysis of Horizon projects focused on the development of new flexibility services.