Objectives: Catastrophic health expenditure (CHE) means that medical spending of a household exceeds a certain level of capacity to pay. Previous studies of CHE have focused on benefits supported by the public sector or high medical cost incurred by treating diseases in South Korea. This study examines variance of CHE in these households according to changes in employment status. We also determine whether a relationship exists according to income level. Design: A longitudinal study. Setting: We used the Korea Welfare Panel Study (KOWEPS) conducted by the Korea Institute. Participants: These data consisted of 5,335 households during 2009-2012. Outcome measure: CHE defined as health expenditures that were 40% greater than the ability of the household to pay. Results: Households with people who experienced changes in job status from employed to unemployed (OR 2.79, 95% CI 2.06-3.78) or were unemployed with no status change (OR 1.57, 95% CI 1.28-1.92) were more likely to incur CHE compared to those who were consistently employed. In addition, low-income families that either lost a job (OR 3.52, 95% CI 2.44-5.10) or were already unemployed (OR 1.67, 95% CI 1.29-2.16) were more likely to incur CHE compared to those with a consistent job. Conclusions: Given the insecure employment status of people with low-income, they are more likely to face barriers in obtaining needed health services. Meeting their needs for health care is an important consideration.