Sitting the CSAT well matters, but completing the registration properly comes first. The same questions repeat every year during the registration window. Why go in person after filling in the form online? Where do graduates file? Can the elective science or social studies subject be changed later? The 2027 CSAT will be held on Thursday 19 November 2026, with registration opening in late August. Here it is in order.

Online pre-entry and in-person filing are two separate steps

This is where it goes wrong most often. Registration is split into two stages. Online pre-entry runs from 09:00 on Thursday 20 August 2026 to 18:00 on Thursday 3 September, while the issue, filing and amendment of forms runs from Monday 24 August to Friday 4 September. In-person filing is from 09:00 to 17:00 and excludes Saturdays and public holidays.

The online stage is exactly what its name says: pre-entry. It records personal details and the sections to be sat in advance so that less time is needed in person; it does not complete the registration on its own. The application is registered only once the form has been filed at the receiving office and the fee payment is confirmed.

The reverse also works: you may skip the online stage and complete the form in person. But queues build on the closing day, so pre-entering and attending early in the window is the safer approach.

The differing start dates need attention too. Online entry opens on 20 August but in-person filing only begins on 24 August, so entering details on the 20th does not let you finish that day. The closing dates differ by a day as well: 3 September online, 4 September in person.

Where you file depends on your status

The second source of confusion is where to go. The test is whether you are currently enrolled at a school.

• Current students — file at the high school you attend. The school handles it collectively, so follow the guidance from your class teacher.
• Graduates — file at the high school you graduated from, or at the district office of education for the test district covering your registered address. If you are at a private academy, it does not file on your behalf.
• Equivalency exam holders and others — file at the district office of education for the test district covering your registered address.

What graduates most often miss is documentation that must be obtained beforehand. If you file at a district office rather than your former school, you may need a school record or graduation certificate to confirm your status. Requirements differ slightly by test district, so check that office's announcement before travelling. What else falls to you to organise is gathered in once you start a repeat year, nobody organises it for you.

The fee is set by the number of sections, and exemptions exist

The fee varies with how many sections you sit: 37,000 won for four or fewer, 42,000 won for five and 47,000 won for six, unchanged from the previous year for 2027.

There is an exemption scheme. Basic livelihood security recipients, those in the statutory near-poverty bracket and recipients of single-parent family support are exempt from the fee. For current students whose social security benefit records are already reflected in NEIS, the exemption is applied automatically without separate documentation. If you may qualify, check with the school or the receiving office before filing.

Refund rules for withdrawing are set out as well. Cancel within the defined period and part or all of the fee is returned; after that period there is no refund. Graduates, who often register and then do not sit, should check that timetable in advance.

Payment can be made online. As noted above, however, payment alone does not complete the registration. Completion is confirmed by the registration receipt.

Elective subjects can only be changed within the window

This is the part that most changes outcomes. Sections and elective subjects can be amended during the registration window, but not after it closes. That is why plans to switch an elective after seeing the September mock results so often fall apart.

Three things must therefore be settled at registration: the electives in Korean and mathematics, the stream and two subjects in the exploratory section, and whether to sit the second foreign language or classical Chinese paper. Decide only after checking which sections are used and which are compulsory in the admissions guides of the universities you intend to apply to. Why the same score produces different outcomes at different universities is covered in the difference conversion scores make.

One more thing. Rushing to change subjects because the September mock looks worse than June is risky. Grades falling because the cohort sitting the paper has changed repeats every year and has nothing to do with a change in ability.

What to check afterwards, and the dates ahead

Once filed, check on the spot that the receipt shows the correct sections and electives, name and resident registration number. The same goes for the photograph; every year some are rejected for not meeting the specification and have to be resubmitted.

From there the calendar runs as follows: the September mock assessment, early admission applications, the CSAT on Thursday 19 November, and the release of result slips on Friday 11 December. Linkage with the public broadcaster's materials remains at around 50 per cent of items by section and subject.

If the standard score, percentile and band on the result slip seem to tell different stories, reading the three numbers on the CSAT result slip alongside it makes the interpretation quicker.

In summary

Online pre-entry (20 August to 3 September) and in-person filing (24 August to 4 September) are both required steps. Current students file at their school; graduates and equivalency exam holders file at their former school or at the district office of education for their registered address.

The fee runs from 37,000 to 47,000 won depending on the number of sections, with a separate exemption scheme. And elective subjects cannot be changed once registration closes. It is more accurate to treat the registration window as the point at which the exam strategy is fixed, rather than as paperwork day. District-level detail is published each year by the metropolitan and provincial offices of education, so open the relevant announcement before you travel. Upper secondary academic and admissions matters continue in the high school board.