The aims of this study were threefold: to provide an overview of approaches to meeting the State aid transparency requirements; to assess the effectiveness of different approaches using available data; and to identify potential changes to the transparency requirements that might improve levels of compliance. The review of reporting arrangements reveals diverse arrangements for compliance with the transparency requirements. Formally, the transparency requirement under the GBER flows from the direct applicability of EU law and in principle does not require further implementation. As a result, in about a third of countries there is no specific State aid legislation. The remaining countries have enacted State aid legislation, but the substance of this varies widely. Variances in the timeliness of reporting are largely driven by the performance of individual granting authorities – a very few bodies account for the majority of delays. A selection of case studies was undertaken and to identify potential changes to the transparency requirements that might improve levels of compliance.