Over 500-thousand employment-based subscribers of the national health insurance system pay additional contributions based on secondary income.

According to a National Health Insurance Service(NHIS) report submitted to Rep. Jung Choun-sook of the main opposition Democratic Party(DP) on Monday, 552-thousand-282 employed individuals incurred additional subscription fees due to extra income as of the end of last year.

The NHIS data showed that such subscribers, accounting for two-point-81 percent of all employment-based subscribers in the nation, pay an average of 200-thousand won on top of their base contribution.

The number of individuals hit with an increased rate rose gradually from 182-thousand-398 in 2019 to 246-thousand-920 in 2021.

However, it more than doubled last year due to the revisions of the national health insurance system that drastically dropped the threshold for incurring the additional contribution fee based on secondary income from 34 million won to 20 million won.