Jobseekers attend a job fair in Daegu, April 17. Yonhap

Kim, a 41-year-old construction worker employed on the night shift at a GS25 convenience store in Seoul's Yeouido financial district, had to get a side job because his wife ended up taking maternity leave beyond the paid period.

"My wife's income was essential for us to sustain a dual-income household, and I can't envision managing loan repayments, bills, and raising children without my side job," Kim said, declining to give his full name.

Kim's situation is emblematic of a growing trend among Koreans in their 40s and younger who are taking on side jobs due to insufficient earnings from their primary jobs, exacerbated by persistently high inflation and a resulting decline in real wages.

The demand for side jobs among Koreans in their 40s and younger has been increasing at a faster rate compared to those aged 60 and older, who were previously the most active in seeking additional sources of income.

According to data from Statistics Korea, on Monday, a total of 552,037 Koreans had one or more side jobs in addition to their primary occupation during the first three months of this year, up 22.4 percent from the same period of 2023.

Those aged 60 and older outnumbered other age groups, accounting for 194,371 individuals, or 35.2 percent of the total. This figure also represented a 25.1 percent increase from the previous year.

However, the rate of increase was more pronounced among individuals in their 40s and those aged between 15 and 29.

The number of people in their 40s with side jobs totaled 115,228, up 27.7 percent from the previous year, and those aged between 15 to 29 stood at 53,000, up 30.9 percent.

Most of the side jobs were linked to online platforms, such as food delivery or content creation on YouTube.

This trend coincides with a decline in real wages, adjusted for inflation, which continued for the second consecutive year in 2023 according to the latest data from the Ministry of Employment and Labor.

The average real wage amounted to 3.55 million won ($2,500) per month, down 1.1 percent year-on-year.

The Korea Labor Institute, a think tank under the labor ministry, assessed that individuals with lower-paying jobs are more likely to take on side jobs. Referring to its own study, the institute noted that individuals with side jobs earn an average of 13,000 won per hour, compared to 16,000 won earned by those with a single job.

"In this context, creating more high-quality jobs is crucial to prevent workers from feeling compelled to seek multiple jobs," it said in the report.

Meanwhile, consumer prices increased 3.1 percent year-on-year in February and March, compared to 2.5 percent in January, when it dipped below 3 percent for the first time since July 2023.