This study examines the challenges faced by the Customs Administration of the Netherlands in supervising cross-border e-commerce imports under the current European customs legislation, the Union Customs Code (UCC). Through a mixed-method approach, including qualitative interviews, document analysis, and simulation modelling, the study identifies potential supervisory actions to strengthen e-commerce import supervision, particularly in anticipation of the proposed UCC reform. The findings indicate the complexities of customs operations and emphasise the need for efficient, fair, and effective enforcement while fostering trust and accountability. The uncertainties surrounding the UCC reform, trade markets, and technological advancements are addressed, with recommendations that focus on strategic automation, stimulating curiosity among customs officers, clear communication, and further research to develop adaptive supervision strategies. These recommendations aim to address core challenges and exploit opportunities for improvement while considering feasibility constraints and potential uncertainties.