The Commission proposal for a reformed Union Customs Code (R-UCC) foresees, besides replacing national customs clearance systems by an EU Customs Data Hub, managed by an EU Customs Authority, a shift of the responsibility from the declarant and holder of a customs procedure to the importer or exporter, i.e., the person determining that the goods are brought into or out of the EU. In its Impact Assessment, and briefly in its explanatory introduction to the proposal, the Commission has analysed and explained the consequences of this shift with regard to standard imports and exports, not, however, with regard to the special procedures, such as transit, customs warehousing and inward processing. The author has therefore completed this missing analysis with the result that the concept of a single liable importer or exporter could work if there existed only a single procedure for import and export. However, the reality is that often several actors are involved in an import/export process with different procedures and processes following each other; these persons may be, besides the carrier, the temporary storage operator, the transit operator, the operator and the user of a customs warehouse, until the goods are finally released for free circulation or export by, or on behalf of, the actual importer or exporter. Furthermore, the focus on the importer and exporter has resulted in a certain neglect of the role of intermediaries in the supply chain, such as customs and logistics service providers, whose services are vital for many small and medium sized companies (SMEs) that cannot afford their own specialized customs staff and IT systems for the handing of imports and exports.