BACKGROUND: Deciding which types of activities require an ethics review is a critical component of research regulation. Reviews conducted by research ethics committees consider the rights and safety of potential research participants, and occur as part of a wider set of governance reviews. However, to save time and resources, projects that do not raise ethical issues, or have ethical issues dealt with through other processes, are defined as out of scope for research ethics review by often being labelled as quality improvement, clinical service evaluation, audit or similar. METHODOLOGY: Here we argue that the problem of identifying projects that need to be reviewed by a research ethics committee is distinct from attempts to define research more generally, and the two contexts must not be confused. RESULTS: We describe a pragmatic, heuristic, solution developed by the authors working with three UK government agencies, with the goal of clarifying which projects/studies require a research ethics review. CONCLUSION: Alongside applying to UK research, our approach will be of interest to international regulators and researchers when considering the wider implications as to where ethics accountability sits for different types of research-related activities.