2026 South Korea Substitute Holidays and Business Days

The Korea Astronomy and Space Science Institute page reproducing the Korea AeroSpace Administration's 2026 calendar summary lists 70 public holidays on the government-office calendar and 118 days off for a five-day-workweek organization. That summary was published on June 30, 2025 and is a calendar-production baseline, not a substitute for a later legal or workplace update.

The same official summary identifies four three-day periods created by substitute holidays in 2026. These dates help with planning, but an operational deadline should still be checked against the current regulation and the applicable organization calendar.

• March 2: substitute holiday following March 1 Independence Movement Day.
• May 25: substitute holiday following Buddha's Birthday on Sunday, May 24.
• August 17: substitute holiday following Liberation Day on Saturday, August 15.
• October 5: substitute holiday following National Foundation Day on Saturday, October 3.

The 2026 annual calendar summary predates an amendment to the Public Holiday Regulation. Presidential Decree No. 36290 added Labor Day on May 1 to the government-office public-holiday list with effect from May 1, 2026. Only the amendment to the overseas-mission proviso and the national-holiday reference took effect on May 11, 2026.

Because the legal text changed after the annual summary was published, do not infer a final holiday count from the older total alone. Use the annual summary for its stated baseline and the current regulation for the rule now in force.

Start with the calendar dates in the period, remove the non-working weekdays used by the organization, then remove applicable public holidays and add any company-specific closure dates. Apply the contract's start-date and end-date inclusion rules last so day 0 and day 1 are not confused.

• Choose the country and year that govern the deadline.
• Set the organization's weekend rule instead of assuming Saturday and Sunday.
• Exclude public holidays only when the selected rule makes them non-working days.
• Add regional, bank, school, company, or contract-specific closures manually.
• Confirm whether the start date and end date are included in the count.

Assume a South Korea schedule starts on Friday, February 27, 2026, excludes Saturdays, Sundays, and applicable public holidays, and does not count the start date. The weekend is skipped, and the March 2 substitute holiday is also skipped. The first counted business day is Tuesday, March 3, so the fifth counted business day is Monday, March 9.

A contract that includes the start date, uses a different weekend, or does not recognize the substitute holiday will produce a different result. Record those assumptions beside the calculated date.

Assume a request is received on Thursday, August 13, 2026 and the rule requires three business days after receipt. The start date is excluded, Saturday and Sunday are non-working, and the organization recognizes the August 17 substitute holiday. Friday August 14 is day 1, the weekend and Monday holiday are skipped, Tuesday August 18 is day 2, and Wednesday August 19 is day 3.

If the governing policy counts the receipt date, the result becomes Tuesday August 18. If a service operates on the weekend or does not observe the substitute holiday, the outcome changes again. This comparison is more useful than copying a national holiday count because it exposes the exact operational assumptions that move the deadline.

For a material deadline, compare three layers. The first is the current national rule and official annual calendar. The second is the regional or industry calendar that may govern banks, markets, schools, logistics providers, or public offices. The third is the organization-specific schedule in the employment policy, customer contract, service terms, or internal closure notice. A date is a business day only under the rule attached to the obligation; it is not determined by the national label alone.

Record which layer supplied each excluded date. This makes later review possible when an API changes, an employer adds a closure, or a counterparty disputes the count. For long-range planning, check the sources again near the deadline instead of assuming a page reviewed months earlier remains complete.

Presidential Decree No. 36290 took effect on May 1, 2026 and added Labor Day on May 1 to the government-office public-holiday list. Its supplementary provision delays only the amendment to the overseas-mission proviso and the national-holiday reference until May 11. For a binding deadline, still confirm whether the governing employer policy or contract follows the government-office calendar.

DeadlineDays therefore separates the older annual-calendar baseline from the later current-rule notice. It does not rewrite the published 70-holiday or 118-days-off totals. This avoids presenting two official materials from different dates as though they were issued together or applied identically to every organization.

Teams planning payroll, shipping, invoice follow-up, or SLA coverage can maintain a small annual exception register. List the official national dates, then add regional and company closures with an owner and source. For every calculation, save the weekend rule, start-date rule, public-holiday option, custom dates, and review date. When an official announcement changes, update the register once and identify the schedules that depend on it.

This method is more reliable than manually editing individual due dates because the assumptions stay visible. It also helps distinguish a data-source correction from a policy decision, such as a company granting a day off that is not a national public holiday.

National public-holiday data does not automatically represent every local closure, bank schedule, school calendar, employer policy, exchange calendar, or contract definition. Temporary holidays and provider-specific operating days can also change after a planning page is reviewed.

DeadlineDays is a planning tool, not an official calendar or legal interpretation. Verify binding dates with the current government source and the organization responsible for the deadline.