Background
In the last decade, almost every low- or middle-income country in the world has expressed support for universal health coverage (UHC). While at the beginning of the UHC movement, country strategies focused on increasing access to the formal sector as the first step of UHC, there is now consensus that countries should cover the entire population, with particular attention to covering the poor. However, it is often assumed that mandatory schemes will automatically cover their target populations, and consequently little is known about why firms comply or do not comply with enrolment requirements.

Using the experience of Lao PDR, where the enrolment rate in the mandatory social security scheme is low and the capacity for regulation is weak, we conducted this study to better understand the determinants of enrolment of private sector firms in mandatory social security.

Methods
We used a cross-sectional case-comparison design, surveying 130 firms. We applied a structured questionnaire to explore determinants of enrolment, specifically looking at firm characteristics (e.g., industry category, ownership); sociodemographic characteristics of company heads; firms’ risk perceptions; details of employment contracts; employee benefits; and exposure to social security. Closed ended questions were analysed quantitatively, while content analysis was applied to open-ended questions. Logistic regression was used to examine the determinants of enrolment.

Results
Smaller privately owned firms in the services industry were the least likely to enrol in social security, while firms in the trade industry were more likely to enrol than firms in manufacturing, construction, or services. The main reason for not enrolling was that firms offered a better package of benefits to their employees, although further investigation of company benefits showed that this was not the case in practice. Additional reasons for non-compliance were lack of knowledge and poor quality of care at government hospitals.

Conclusions
The study contributes to the dialogue on how best to increase coverage in the formal sector, which is an important element of achieving UHC. It also provides much needed information about the motivation of private sector firms to comply with mandatory schemes.