CBAM transitional period: roles and responsibilities

EU’s Carbon Border Adjustment Mechanism (CBAM) regulation entered its transitional phase on 1st October, 2023. From that day on, importers have to collect and report data on greenhouse gases emitted during the production of CBAM goods. Since the data must be collected from the manufacturers in non-EU countries, a process must be established for the corresponding communication. Given the complexity of supply chains, this process may involve multiple actors between the importer and third country facilities. In addition, several EU and national authorities are involved. Who is/can be who? Who does what? What are the responsibilities?