The law supersedes one of the country’s traditional methods, where individuals are considered a year old at birth, accounting for the time spent in the womb.

Under the “Korean age” system, people would increase their age by a year on 1 January every year, rather than on their actual birth date. For example, someone born on New Year’s Eve would become two years old on New Year’s Day.

Conversely, the other traditional system, known as “counting age”, considers a person zero at birth, with their age increasing by one year each 1 January. According to this method, someone born on New Year’s Eve would turn one on New Year’s Day.

Since the early 1960s, South Korea has adopted the international standard of beginning from zero at birth and adding a year on every birthday for medical and legal documents. Yet, many South Koreans continued to use the traditional method in other aspects of life.

Choi Hyun-ji, a 27-year-old office worker in Seoul, said: “I was about to turn 30 next year [under the traditional Korean age system], but now I have some more time earned, and I love it.”

Mr Choi added: “It’s just great to feel like getting younger.”