The Ministry of Education said Sunday it has ordered a study on private education spending of those taking state-administered college entrance exam multiple times, in a bid to figure out a more accurate estimate of the private education sector in South Korea.

According to the ministry, 31.7 percent of college entrance exam takers in 2023 had already graduated from high school, an increase from 23.2 percent in 2017. South Korean students take the annual exam, known as Suneung, in the last November of high school, but they are free to take the test again to get better grades.

The Education Ministry compiles the private education spending by elementary, middle and high school students for each year, but the spending by Suneung retakers -- called "N-susaeng" here -- are not covered. This has led to concerns that the private education spending in the country is substantially underappreciated in the official tally, since private institutes for N-susaeng conventionally cost more.

Unofficial reports by local media outlets and websites specializing in information related to private education show that cram schools for N-susaeng sometimes charge over 2 million won ($2,220) per month, including the cost of the study materials and meals. Many of these institutes provide lodging, which brings the costs to well over 3 million won.

The total number of Suneung retakers last year was 159,742, meaning they are spending what could be hundreds of billions of won in private spending that are not included in the official government figure.

In a joint report by the Education Ministry and Statistics Korea announced last month, South Korean students spent a total of 27.1 trillion won on private education last year.

"This year's study will be about analyzing the sample group and developing a reliable analysis model for further N-susaeng study. ... A budget has been applied to the authorities for a test study for next year, and (the ministry) will discuss with the Statistics Korea on how the research will be conducted," a ministry official said.

The upcoming study will include specific measures on surveying the private education spending of the multiple Suneung-takers -- such as to include those who prepare by themselves at home through online lectures -- and the exact definition of N-susaeng, which had been loosely defined by media outlets and education authorities up to this point.

N-susaeng conventionally refers to young students preparing for the college exam. But sometimes it also includes college graduates who have a job but decided to have another go at the college entrance exam.