South Korea passed laws to scrap its traditional method of counting ages and adopt the international standard.
The shift will make its citizens one or two years younger on official documents.
South Korean citizens are deemed to be a year old at birth and a year is added every January 1. This is the age most commonly cited in everyday life.
A separate system also exists for conscription purposes or calculating the legal age to drink alcohol and smoke, in which a person's age is calculated from zero at birth and a year is added on January 1.
However, since the early 1960s, South Korea has for medical and legal documents also used the international norm of calculating from zero at birth and adding a year on every birthday.
The confusing array of systems will disappear — at least on official documents — when the new laws that stipulate using only the international method of counting ages take effect in June 2023.
“The revision is aimed at reducing unnecessary socio-economic costs because legal and social disputes, as well as confusion, persist due to the different ways of calculating age,” Yoo Sang-bum of the ruling People Power Party told parliament.
Office worker Jeong Da-eun, 29, said she always had to think twice when asked overseas about her age.
“I remember foreigners looking at me with puzzlement because it took me so long to come back with an answer on how old I was,” she said.
“Who wouldn't welcome getting a year or two younger?”