Kiribati celebrates New Year's Eve earliest among countries because Kiritimati lies in the UTC+14 time zone.
Kiritimati, also called Christmas Island, is part of Kiribati's Line Islands. The islands use Line Islands Time, which is 14 hours ahead of Coordinated Universal Time, making them among the first inhabited places to reach January 1.
Kiribati moved the International Date Line eastward around its eastern islands in 1995. The change aligned the country's widely separated island groups on the same calendar day, rather than leaving some islands nearly a day behind others.
The claim is about time-zone position, not a universal contest over one exact first street or household. Other Pacific locations also reach the new year very early, and the order can depend on whether a source is discussing sovereign countries, inhabited islands, or settlements.