A total of 10,185 government officials in South Korea made more than 20 million won ($15,000) in annual income in addition to their salaries in 2023, National Health Insurance Service data showed Friday.

The data, provided by Rep. Choi Hye-young of the main opposition Democratic Party of Korea, revealed that 0.67 percent of the 1.51 million civil servants currently enrolled in the National Health Insurance program are paying monthly premiums based on their income and assets. The monthly premium is mandated for those making annual nonsalary income exceeding 20 million won.

South Korean law bans civil servants from having another job in principal, but exceptions can be made with the permission of the head of one's agency. The means of profit conventionally can include rental revenue, banking interest, stock dividends and business profits.

The National Health Insurance program requires a monthly subscription fee of 7.09 percent for salaried workers, but the amount of the monthly premium is proportionate to the size of the extra income. There is, however, an upper limit to the premium, which is 30 times the average subscription fee of salaried workers for two years prior.

The NHIS report showed that 12 civil servants paid the upper limit for the monthly premium, which for 2023 was 3.91 million won. The minimum estimated extra annual income for those people, calculated based on the monthly premium, comes out to 682 million won.

The number of government officials paying additional subscription fees has been on the rise each year, from 2,000 in 2019 to 2,519 in 2020, 3,179 in 2021 and 9,080 in 2022. The increase in 2023 is partially due to the government changing the previous threshold for paying premiums -- which had been extra income of over 34 million -- to over 20 million won in additional income, starting in July 2022.

A NHIS report revealed earlier this month that 607,226 salaried workers in total are making enough extra income to pay the premium. There were 4,124 salaried workers paying the maximum premium.