Introduction Informal employment has been conceptualised as an employment condition and as a social determinant of health because of its impact on self-reported health and health inequalities. However, currently evidence on the effects on health is scarce and its definition remains unclear. The aim of this study was to propose a new conceptualization of the working population in Chile, in order to make visible different groups of workers in informal employment, focusing on social protection as a key element in the definition of informal employment status.

Methods We developed a mixed strategy combining a literature review, key informant interviews and epidemiological analysis. We reviewed scientific and grey literature (documents from international organisations and public institutions). Ten interviews were conducted with persons from different backgrounds and approaches to the Chilean labour market. To describe the groups from a social protection perspective, we analysed data for 8,357 workers from the first Chilean work, employment health and quality of life survey (2009–2010).

Results Based on the information gathered, the following five variables were selected to generate, in combination, 13 groups of workers: status in employment, contractual status and workplace for dependent workers, educational level for self-employed and number of employees for employers. The social protection status of these 13 groups was analysed based on contribution to pensions scheme as a central axis, aiding to identify them as formal or informal.

Conclusions This new classification makes it possible to unravel groups of workers who had been previously excluded by dichotomist approaches to informal employment, confirming that a more nuanced approach is required to overcome the invisibility of certain types of workers, which may otherwise have important consequences on their health. Having a more precise classification leads to an improved measurement of informal employment and a better understanding of its impacts on population health.