Corruption is a major challenge in health care systems across the European Union (EU), where it manifests most visibly as informal payments from patients to providers. A higher prevalence of informal payments has been associated with lower public health care expenditure. EU member states have experienced significant changes in public health care expenditure throughout the 2000s. Given the lack of research on the topic, we explored trends in informal payments using representative data from twenty-eight EU member states during the period 2013-19 and in relation to changes in public health care expenditure. Overall, we found that informal payments increased in 2019 compared with 2013, whereas the perception of corruption decreased. Although higher public health care expenditure was associated with less corruption, we found a smaller effect size between informal payments and this expenditure throughout the study period. Our results suggest that informal payments may be driven by other factors, although the directionality of this relationship requires further investigation. Moreover, additional public health care investments may be insufficient to confront corruption unless coupled with measures to limit wasteful spending and increase transparency. Policy makers should understand that factors external to health systems, including media coverage and cultural and political factors, should be explored to explain country-level differences in corruption.