Like most of the central legal questions in the field of civil law, the question when a debt becomes time-barred is not harmonized within the EU, but is governed by rules at national level. This applies normally even in situations where the grounds of the claim itself are based on EU legislation. In this situation the applicable national rules must meet the requirements of equivalence and effectiveness. The requirement of effectiveness provides that national procedural rules must not render the exercise of rights conferred by EU law virtually impossible or excessively difficult. This article analyses under what circumstances national limitation rules may become inconsistent with the principle of effectiveness. [---]