In South Korea’s National Health Insurance (NHI) contribution system, insurance premiums are imposed differently according to subscriber type. The contribution of employees is calculated based on earned income, whereas the contribution of the self-e...
In South Korea’s National Health Insurance (NHI) contribution system, insurance premiums are imposed differently according to subscriber type. The contribution of employees is calculated based on earned income, whereas the contribution of the self-employed reflects various factors such as income, property, and automobile ownership. As a result, differing assessment criteria have led to continued concerns about regressivity. To address these issues, the government implemented two stages of income-centered reforms to the NHI contribution system in July 2018 and September 2022.
This study empirically analyzed changes in the equity of contribution assessment according to subscribers’ ability to pay, following the first and second-stage reforms. Specifically, it compared the level of contributions relative to income between employee and self-employed subscribers to examine how equity changed before and after the reforms.
The analysis covered four time points—before the reform (2017), after the first-stage reform (2019, 2021), and after the second-stage reform (2023)—and used two indicators: the decile ratio and the Kakwani progressivity index. Two data sources were employed: the Korea Health Panel Survey (KHPS) and the National Health Insurance Service (NHIS) administrative data. The KHPS was used to generate simulated premium variables, while the NHIS data, based on actual administrative records, were utilized for cross-validation.
The results show that the shift toward an income-centered contribution system alleviated regressivity among low-income groups and more appropriately reflected the ability to pay among high-income groups, thereby improving the vertical equity of premium assessment compared with the pre-reform period. Specifically, for employees, the second-stage reform strengthened the criteria for non-wage income and raised the premium ceiling, resulting in a relative increase in the burden on high-income earners. For the self-employed, the introduction of a minimum contribution and the expansion of property deductions reduced the burden on low-income groups; however, the property deduction also partially benefited high-income groups, resulting in a simultaneous decrease in their contribution burden.
In summary, although the reforms contributed to overall improvements in equity, the structural duality between employees and the self-employed has not been fully resolved, and certain limitations remain in achieving complete fairness in the contribution system.