Korea's Unified Age Act: What Changed, What Didn't

Amendments effective June 28, 2023 established international age as the default calculation and display rule in Korean civil and administrative law unless a special rule applies. They did not ban colloquial Korean age or rewrite every program at once. Military service, youth protection, and school enrollment have separate statutory or birth-cohort rules, so always check the governing rule and reference date.

1. Three Age Systems

• International age — age from birthday (0 at birth, +1 per birthday)
• Year age — current year − birth year
• Korean age — 1 at birth, +1 on each Jan 1. It is not the civil or administrative default, but colloquial use was not outlawed or abolished.

2. What the Unified Age Act Changed

Under the Civil Act and Framework Act on Administrative Affairs, an age in a statute, contract, or public document is generally calculated and displayed by international age unless a special provision says otherwise. A program may instead set a birth-year cohort, reference date, or another express rule, which controls over a generic age calculation.

3. Major Programs With Special Age Rules (2026)

① Military service

Men subject to the military-service duty generally undergo the examination in the year they turn 19 by year age. In 2026, that means the 2007 birth cohort, regardless of birthday. Check the Military Manpower Administration notice for the actual schedule, deferments, and exemptions.

② Youth Protection Act (alcohol/tobacco)

Article 2 of the Youth Protection Act defines a youth as a person under 19 but expressly excludes anyone who has reached January 1 of the year in which they turn 19. This is a statutory exception, not merely shop practice. Thus a person born in 2007 is outside that Act's youth definition from January 1, 2026, but other laws may use different tests.

③ Elementary school enrollment

The Elementary and Secondary Education Act generally requires enrollment on March 1 of the year after the year in which the child turned six. The ordinary 2026 cohort is therefore children born in 2019, not children whose 2026 year age is six. Early entry, delayed entry, deferment, and exemption can alter the result, so use the enrollment notice and education-office guidance.

4. Everyday Implications

• Friend groups — Korean "same-age peers" is a year-age concept.
• Vaccination programs — check the birth-date range in each season's notice; national flu programs can use a cohort cutoff tied to the season's starting year rather than age on the vaccination date alone.
• Labor rules — international age may be the starting point, but work permits, school status, and restricted duties can add separate requirements. Do not infer eligibility from the calculator alone.

5. Common Confusion Post-Reform

In statutes, contracts, and public documents, a bare reference to age generally means international age unless a special rule applies. People born in the same year can therefore have different ages on a given date depending on whether their birthday has passed. Colloquial use of Korean age or year age is not prohibited, but eligibility and contracts should identify both the reference date and calculation rule.

6. Calculators

• Korean Age Calculator — compares international, year, and traditional Korean age