This contribution focuses on the so-called passing-on problem in actions for repayment of charges levied by Member States in breach of EU law. ‘Passing-on’ occurs when the economic burden of a charge levied from a business is passed on to burden that business’ customers, and possibly even further down the supply chain. [---] Using examples from their home jurisdictions Sweden and Norway, the authors demonstrate that the passing-on problem is a multi-million euro issue which remains governed by diverging national laws, albeit subject to some restrictions developed by the Court of Justice in the absence of EU harmonization. With a view to safeguarding legal certainty, the effective protection of EU law rights, and the elimination of random discrepancies among national rules that are crucial to the proper functioning of the internal market, the authors call for EU harmonization of the legal issues triggered by passing-on. To that end, the authors present two alternative models for harmonization.