Why Korean Age Changed, the 2023 Law Explained

For decades, a question as simple as "how old are you" could have three different correct answers in Korea, depending on which counting system was being used. A 2023 law changed that for legal and administrative purposes, and the mechanics of what exactly changed are more specific than "everyone got younger."

The three systems Korea had been using

According to Korea.net, the government's official news portal, Korea used three separate ways of counting age before the reform:

• "Korean age" (the traditional system): a baby is considered 1 year old at birth, and everyone gains a year on January 1st, regardless of their actual birth date.
• The yearly age method: calculated simply as the current year minus the birth year, with no adjustment for whether the birthday has happened yet.
• Full-year (international) age: starts counting from 0 at birth, and a year is added only on each individual birthday.

These three systems could each produce a different number for the same person on the same day, which the Ministry of Government Legislation, announcing the reform, described as a genuine source of social and administrative confusion.

What the law actually did

On June 26, the Ministry of Government Legislation announced that the full international age counting system would take effect from June 28, 2023. According to Korea.net's reporting on the announcement, the reform required the use of the full-age system specifically in legal and public documents and contracts going forward. The Seoul Foreign Portal, run by the Seoul Metropolitan Government, confirms the specific mechanics: starting June 28, 2023, the General Act on Public Administration and the Civil Act took effect to standardize international age counting, and the portal spells out the exact formula:

• If your birthday hasn't occurred yet this year: your age is (current year − birth year − 1).
• Starting from your birthday this year: your age is (current year − birth year).

That is precisely the international age system almost everywhere else already uses. The difference from Korea's prior "Korean age" system is the starting point (0 at birth instead of 1) and the increment point (your actual birthday instead of every January 1st).

How much younger this made people, on paper

Because the traditional Korean age system counted a newborn as already 1, and added a year to everyone on January 1 rather than on individual birthdays, the gap between Korean age and international age was always either 1 or 2 years, depending on whether a person's birthday had already passed in the current year. Korea.net's reporting describes this precisely: the standardization made every Korean a year or two younger on paper than their previous "Korean age," because the law shifted all legal and official age references onto the international formula described above.

Why this was a legal change, not a cultural one

It's worth being precise about scope, since this point gets blurred in casual explanations. The reform standardized age for legal and administrative purposes: contracts, official documents, and public administration, per both the Korea.net report and the Seoul Foreign Portal's description of the General Act on Public Administration and Civil Act. It did not abolish the traditional Korean age counting custom as a social or cultural practice; Koreans can still refer to "Korean age" informally in conversation. What changed is which number carries legal weight on a form, a contract, or in an age-based law or regulation.

Where age-based rules already used a different standard

One nuance worth knowing: some Korean laws, particularly those around alcohol, tobacco, and certain age-based eligibility rules, had already used a "calendar year age" (the current year minus birth year, without an exact-birthday adjustment) well before the 2023 reform, rather than either the traditional Korean age or the newly standardized international age. The 2023 law's main effect was unifying the general default used across contracts and everyday legal documents onto the international system; it's still worth checking the specific wording of any individual age-based rule in Korea, since calendar-year age continues to apply in certain specific statutes.

Key takeaways

• Before June 28, 2023, Korea used three overlapping age systems: traditional "Korean age" (1 at birth, +1 every January 1), calendar-year age (current year minus birth year), and international age (0 at birth, +1 on each birthday).
• The Ministry of Government Legislation's reform, effective June 28, 2023, standardized legal and administrative age onto the international system via the General Act on Public Administration and the Civil Act.
• Under the new standard: your age is (current year − birth year − 1) before your birthday this year, and (current year − birth year) from your birthday onward.
• The reform made people one to two years younger on official documents, but it changed the legal default, not the traditional social custom of referring to "Korean age" informally.