Medical certification in sickness benefit schemes (I): theoretical perspectives and return-to-work

This study explores the theoretical foundations and practical applications of medical certification within the sickness benefit systems, particularly in the context of Korea's pilot program and its planned national rollout. While sickness benefit systems have long existed in many Organization for Economic Cooperation and Development (OECD) countries, Korea has only recently initiated pilot projects, largely prompted by the coronavirus disease 2019 pandemic. These systems aim to compensate for income loss due to illness or injury, and medical certification plays a central role in determining eligibility and work ability. This study defines medical certification as a two-stage process: clinical diagnosis and formal assessment of a worker's ability to return-to-work. The dual nature highlights the distinct objectives of the medical treatment and social security policies. Drawing on international practices, this study reviews the International Classification of Functioning, Disability, and Health (ICF) as a key global framework for assessing disability and work ability, although it acknowledges the limitations of its application to sickness benefits. The research emphasizes a shift in global trends toward return-to-work-oriented certification models, such as the UK's "fit note" system, which focuses on evaluating fitness-for-work rather than merely documenting illness. Sweden and Japan also offer models that integrate rehabilitation with flexible work accommodations. Three key issues were identified in Korea's system: the role of medical certification and concerns about moral hazard, the burden of proof and workload on physicians, and public perceptions of the program's purpose. We believe that medical certification should not only verify illness but also support early intervention and a healthy workforce. Ultimately, this study advocates for a balanced and efficient medical certification system tailored to Korea's healthcare context closely aligning with labor market policies to ensure long-term sustenance and integration of the sickness benefit program.