We show that many individuals are not well informed about the pension rules applicable to them and that individuals with lower education and lower numeracy skills fail to update their knowledge when affected by pension reforms. Moreover, the effect of pension reforms on individuals’ labour supply decisions is driven by well-informed individuals. This is the first study to separate information gathering from labour supply decision making, thus providing a causal link between the knowledge of pension rules and individuals’ labour supply behaviour. Pension policies could potentially be more effective if individuals were adequately informed.