If you have three children and the first or second is already in high school, it is natural to want the youngest to attend the same school. From the 2027 school year, Seoul lets the second or later child of a family with three or more children ask to be assigned to the high school a brother or sister already attends. Until now that applied only to twins. It is not open to every school, though, and there are conditions on the sibling's grade and on the type of school. This article is based on the Seoul Metropolitan Office of Education's "2027 Seoul High School Admission Basic Plan", published on 31 March 2026 and checked on 20 October 2026.

Same-school assignment, once for twins only, now covers multi-child families

The "special assignment" section of the basic plan lists twins together with multi-child families (children of a person with three or more children) and the brothers and sisters of students with severe disabilities.
Twins must apply to the same school within their home school zone and give the same order of preference. Children of multi-child families and siblings of students with severe disabilities need no such matching: if they ask to go to the school their sibling attends, they qualify for same-school assignment.

Only the second and later children qualify; the first child is assigned in the usual way

The plan says a child in a multi-child family can be assigned to the school a sibling attends starting from the second child, while the first child goes through the general assignment.
For example, if the eldest of three siblings is in Grade 11 and the second is in Grade 9, the second child can ask for the eldest's school. If the eldest is in Grade 9 and the younger ones are in primary school, the eldest has no sibling in high school to follow and goes through the normal procedure. A family with only two children does not fall under this rule unless they are twins.

The sibling must be in the first or second year of high school on the application date

This is the condition people miss most easily. A note in the basic plan says the rule applies only if the sibling is in the first or second year of high school on the application date. For Seoul's superintendent-selected late-round high schools, applications run from 3 to 7 December 2026.
So if the sibling is in the third year or has already graduated at that point, you cannot ask for the same school. A sibling who is in middle school or university does not count either. For the sibling of a student with a severe disability, the same logic applies: the student must be in the first or second year of high school on the application date.

Only superintendent-selected late-round schools count, so check the sibling's school first

The plan states that this special assignment applies only to superintendent-selected late-round high schools. For the 2027 school year Seoul has 212 of them, starting with Garak High School, and the list is on the Seoul high school information site HiInfo (hinfo.sen.go.kr).
Schools that choose their own students, such as foreign language high schools, international high schools, autonomous private high schools, specialised high schools and Meister high schools, cannot be reached through this rule. First check which kind of school your sibling attends. If the sibling attends a school outside Seoul, Seoul's same-school rule does not apply, and you should follow the other province's education office.

You must still pass the grade test first, and places are within quota

Same-school assignment does not ignore grades. The plan says special assignees are selected by the same criteria as the assignment candidates chosen in the superintendent-selected late round. In other words, the child must first clear the step in which candidates are picked up to the admission quota, using middle school grades calculated by the superintendent on an absolute-evaluation basis.
Only then is the child assigned to the sibling's school, and the places are within the school's quota. The general application structure at this stage (two different schools in stage one, two schools in the home school zone in stage two) is covered in High school assignment results can be changed, not appealed.

Applications run 3 to 7 December, and assignments are announced on 28 January

The main dates in the basic plan are as follows.

• Applications: 3 December (Thu) to 7 December (Mon) 2026, at the middle school of origin
• Announcement of assignment candidates (admission): 6 January 2027 (Wed)
• Announcement of assigned schools: 28 January 2027 (Thu)
• Enrolment: 28 January (Thu) to 29 January (Fri) 2027

The plan itself says these dates may change depending on school circumstances. For the overall flow of early and late rounds, see The high school admission process already starts in August.

Pre-enrolment assignment after a move follows the same condition

The "pre-enrolment assignment" that opens for cases such as a move after the main assignment also includes same-school assignment for multi-child families, under the same condition: the sibling must be in the first or second year of high school on the application date.
Online applications and document submission for pre-enrolment assignment run from 2 February (Tue) to 4 February (Thu) 2027, and assigned schools are announced on 18 February (Thu). You cannot choose the school this way, and the available places are vacancies plus 3% of each school's quota (outside the quota). Detailed implementation plans are due to be announced in December 2026.

Order of steps and where to check

1) Confirm that the family has three or more children and that the applicant is the second or later child. 2) Check that the sibling is in the first or second year of high school on the December application date. 3) Check that the sibling's school is on the HiInfo list of superintendent-selected late-round schools. 4) When you submit the application to the middle school on 3 to 7 December, ask about requesting same-school assignment and what proof is needed.
The basic plan itself has no list of supporting documents and no application form. For the exact method and documents, check the December application guidance, your middle school, and the Seoul Office of Education (education call centre 02-1396). Support for multi-child families at university level is covered in The multi-child national scholarship. This article does not replace the official guidance of the education office.