The short answer: the 1872 Meiji calendar reform, and three countries that still keep the Lunar New Year
Japan's New Year's Day falls on January 1 because of the calendar reform the Meiji (明治) government decided on in 1872. In November 1872 (Meiji 5), the government announced it would switch to the solar calendar. The new calendar came into use in 1873 and is still in use today.
Korea, China and Vietnam, by contrast, still schedule their holidays around the Lunar New Year. Korea gives three public holidays: the day before Seollal, Seollal itself and the day after. China and Vietnam each set a nine-day holiday period for the 2026 Lunar New Year. Those nine days, however, are not all public holidays. China's nine days include Sundays and adjusted days off, while Vietnam's combine five statutory public holidays with four weekly days off.
The 1872 Meiji reform and the Senmyō calendar, according to the National Diet Library
Japan's National Diet Library (国立国会図書館) explains the background to the reform. From 862, Japan compiled its calendar each year on the basis of China's Senmyō calendar (宣明暦). According to the library, after more than 800 years with the same system, the calendar had drifted out of step with reality. The Meiji government wanted to bring Japan's calendar into line with those of Europe and America, so it announced a switch to the Gregorian calendar.
The changeover was extremely abrupt. The library's Japanese-language commentary describes the situation directly. In English, the passage reads: "There was almost no time to prepare, and what would have been the 3rd day of the 12th month of Meiji 5 became January 1 of Meiji 6 under the new calendar, so the country was thrown into confusion." The library's English-language commentary adds that the first solar calendars had not reached every part of the country by the end of 1872.
The new calendar did have supporters. Scholars such as Fukuzawa Yukichi backed the Gregorian calendar and published books explaining it. Readers can consult the original Japanese and English texts in the calendar (koyomi) section of the National Diet Library website.
An 1872 U.S. diplomatic record and Japan's national holidays law
The switch also appears in records held by the U.S. State Department's Office of the Historian. Japan's foreign minister, Soejima Taneomi (副島種臣), sent a letter dated the 19th day of the 11th month of Meiji 5 informing the American minister of the calendar change. The letter announced that Japan would adopt the new solar calendar and treat the coming 3rd day of the 12th month as January 1. The American minister, DeLong, then reported to the Secretary of State on December 21, 1872, that Japan had adopted the American and European calendar.
Today, Japan's New Year holiday is set by law. The Act on National Holidays (国民の祝日に関する法律) designates 16 days a year as national holidays, among them Ganjitsu (元日), New Year's Day, on January 1. Its stated purpose is to celebrate the beginning of the year. National holidays are designated as days off. A Kyunghyang Shinmun article reports that Japan adopted the solar calendar in 1872 and officially abolished the lunar calendar.
Korea's Seollal from 1896 to 1999, according to the National Archives of Korea
Korea, too, once treated the solar New Year as its official New Year. According to the National Archives of Korea, the country adopted the solar calendar from January 1, 1896, as part of the Eulmi Reforms (乙未改革), and from then on January 1 was the official New Year's Day. The Kyunghyang Shinmun notes that January 1 of the first year of Geonyang (建陽) corresponded to the 17th day of the 11th lunar month of the Eulmi year.
Policies favouring the solar New Year continued after that. A National Archives document states: "In 1949 the government designated the solar New Year (January 1–3) as public holidays." The same document explains that a policy of celebrating only the solar New Year (新正單一過歲) remained in place afterwards. The Kyunghyang Shinmun, meanwhile, reports that from 1970 city dwellers flocked to the countryside every Lunar New Year, giving rise to the phrase 'the great national migration'.
The Lunar New Year became a public holiday in stages. In 1985 it became a one-day holiday under the name 'Folk Day'. In 1989 it regained the name 'Seollal' and the holiday was extended to three days. From 1999, only January 1 remained as a solar New Year holiday. The timeline can be checked in the newsletter on the National Archives of Korea website.
Lunar New Year holiday rules in Korea, China and Vietnam for 2026, compared point by point
In Korea, the current legal basis is the Regulations on Holidays of Government Offices. They were partially amended on April 30, 2026, by Presidential Decree No. 36290, effective May 11, 2026. The regulations designate the day before Seollal, Seollal and the day after (the last day of the 12th lunar month and the 1st and 2nd days of the 1st lunar month) as public holidays. If the Seollal holiday overlaps with a Sunday, a substitute holiday applies. The Ministry of Personnel Management lists both January 1 and the three days of Seollal as traditional festival public holidays.
Set side by side, the three countries differ as follows. On who sets the holiday: in Korea it is a presidential decree, in China the General Office of the State Council (国务院办公厅), and in Vietnam Prime Minister Pham Minh Chinh approved a proposal from the Ministry of Home Affairs. On the 2026 dates: China's Spring Festival (春节) runs nine days, from Sunday, February 15, to Monday, February 23, and Vietnam's Tết runs nine days, from Saturday, February 14, to Sunday, February 22. On what makes up the nine days: China's schedule combines days off with adjusted working days, designating Saturdays February 14 and 28 as working days, while Vietnam's consists of five statutory public holidays under the Labour Code plus four weekly days off.
The rules for overlapping holidays also differ. Korea applies substitute holidays. In Vietnam, when a weekly day off coincides with a public holiday, Article 111 of the Labour Code requires a compensatory day off on the next working day, and employers must notify staff of the holiday schedule at least 30 days in advance. China's 2026 solar New Year (元旦) holiday lasts three days, from January 1 to 3. The Kyunghyang Shinmun reports that Southeast Asian countries also generally celebrate the Lunar New Year.
| Country | Solar calendar adopted | Solar New Year holiday | Lunar New Year holiday | Main sources |
|---|---|---|---|---|
| Japan | Announced November 1872, in effect 1873 | Ganjitsu, January 1 (one of 16 national holidays) | Not confirmed | National Diet Library |
| Korea | January 1, 1896 (Eulmi Reforms) | January 1 only (since 1999) | Three days: the day before Seollal, Seollal and the day after | National Archives of Korea; Regulations on Holidays of Government Offices |
| China | Not confirmed | 2026 New Year (Yuandan): January 1–3, 3 days | February 15–23, 2026, 9 days (including adjusted days off; February 14 and 28 are working days) | Xinhua (General Office of the State Council schedule) |
| Vietnam | Not confirmed | Not confirmed | February 14–22, 2026, 9 days (5 statutory public holidays + 4 weekly days off) | Vietnam Government News; Viet Nam News |
Summary
Japan announced the switch to the solar calendar in November 1872 and implemented it in 1873, and Japanese law today fixes Ganjitsu on January 1. Korea adopted the solar calendar in 1896 but restored the Lunar New Year holiday in two steps, in 1985 and 1989. China and Vietnam set nine-day holiday periods for the 2026 Lunar New Year, though those nine days include weekends and adjusted days off.
Even among East Asian neighbours, the basis for the New Year holiday varies this much. Arguably, the differences can be traced in each country's records on how it set its calendar and holidays. When comparing figures, keep the number of public holidays separate from the length of the holiday period.
