Kiribati is commonly identified as the first inhabited country to welcome the New Year because of its time zone.
The Pacific island nation includes the Line Islands, whose official time is UTC+14. Kiritimati, also called Christmas Island, is the best-known inhabited island in that time zone. When midnight arrives there, much of the world is still on the previous calendar date.
Kiribati moved the International Date Line around its eastern islands in 1994. The change unified the country’s calendar day, which had previously placed its island groups on different sides of the date line. The Line Islands consequently became some of the earliest places on Earth to begin a new calendar day.
The exact “first” can depend on whether a source means a country, an inhabited settlement, or a particular territory. Kiribati is the standard country-level answer, while nearby Samoa and Tonga also celebrate very early in the Pacific.