Data showed that a subscriber would have to earn at least 4.34 million won a month, categorized as top-level income, and stay subscribed for 30 years in order to reach the minimum amount needed for senior life.

According to separate data from the Ministry of Health and Welfare, an average pension subscriber as of this year was enrolled for just 17 years, meaning they receive much less than the estimated amount. For instance, people making average income and who paid into the pension for 20 years would only get 450,000 won.

South Korea's aging society has put a strain on the NPS which is saddled with growing payment needs. The nominal income replacement ratio for 40-year enrollment was as high as 70 percent in 1988, but it fell to 60 percent in 1998 and a further to 50 percent in 2008. By 2028, it could go as low as 40 percent. As of this year, the ratio stood at 45.5 percent.

The rate for an average subscriber enrolled for 17 years would stop at 24 percent.

"We have to increase the amount of pension input at a reasonable level through social consensus on the principle that appropriate payment should be commensurate with appropriate benefits," Rep. Nam said. (Yonhap)