Military Discharge Date
Overview
Korean conscripts serve a period fixed by branch, and the discharge date is computed as the enlistment date plus that duration less one day, because the day of enlistment itself counts as the first day of service. Army and Marine conscripts serve 18 months, Navy 20 months, and Air Force and social service personnel 21 months. A soldier entering the Army on 15 March 2026 therefore leaves on 14 September 2027. The durations reflect a phased reduction completed in 2021, down from 21, 23 and 24 months respectively, and further cuts have been debated against the demographic decline in the conscript pool. Individual dates can shift: disciplinary confinement, unauthorised absence and medical leave beyond an allowance extend the term, while early discharge is granted for medical reasons or family hardship.
Variables
| Symbol | Name | Unit | Description |
|---|---|---|---|
| $D_{in}$ | Enlistment date | date | The date of entry into service, which counts as day one. |
| $Duration_{branch}$ | Service period | months | 18 months for army and marines, 20 for navy, 21 for air force and social service. |
| $D_{out}$ | Discharge date | date | The last day of service, on which discharge takes effect. |
Inclusive Counting
Korean conscript service is measured in whole months from the enlistment date, with the enlistment day itself counted as served:
$$D_{out} = D_{in} + Duration_{branch} - 1$$
The subtraction of one day is the inclusive-counting correction. Adding eighteen months to 15 March 2026 gives 15 September 2027, but because 15 March was already day one the discharge falls on 14 September 2027.
Service Periods by Branch
| Branch | Months |
|---|---|
| Army (육군) | 18 |
| Marines (해병대) | 18 |
| Navy (해군) | 20 |
| Air Force (공군) | 21 |
| Social Service (사회복무요원) | 21 |
The three-month spread between army and air force reflects the training investment each branch makes rather than any difference in obligation, and it is the main reason applicants weigh branch against duration when volunteering.
Month Arithmetic Before Day Arithmetic
Adding months, then subtracting a day, is not the same as adding a fixed number of days: months differ in length, so an eighteen-month term spans between 546 and 550 days depending on the start date and on whether a 29 February falls inside it.
Derivation & History
Inclusive counting is the older convention in Korean legal and administrative practice, in which a period that begins on a given day includes that day. Service terms are stated in months rather than days because conscription intakes and discharges are administered on a monthly cycle; expressing the term in days would give discharge dates that drift relative to the intake calendar. Service periods have been shortened repeatedly since the 1990s, when army service ran to 26 months, and the current durations date from the 2018 reduction schedule.
Worked Examples
Army enlistment on 15 March 2026
- Add the service period in months: 2026-03-15 + 18 months = 2027-09-15
- Apply the inclusive-counting correction: subtract one day
- Discharge: 2027-09-14
Result: 14 September 2027
Edge Cases & Limitations
End-of-month enlistment clamps: adding months to 31 January produces a date that does not exist in the target month, so implementations clamp to the last valid day before subtracting the correction.
Leap days lengthen the term in absolute days: a term spanning 29 February serves one more calendar day than an otherwise identical term that does not.
Early discharge shifts the date: accumulated leave or a designated early release date supersedes the calculated value.
Social service runs on the same arithmetic: alternative service uses an identical expression with a 21-month duration, despite a different administering body.
Real-World Applications
Conscripts and their families use the calculated date to plan university re-enrolment, employment start dates and lease terms, since the discharge date fixes the earliest possible return to civilian commitments. The Military Manpower Administration publishes the same arithmetic in its enlistment notices, and employers verifying completed service check the discharge certificate against the enlistment date and branch duration.