The Pacific island country using UTC+14 on Kiritimati, making it among the first places to enter each New Year, is Kiribati.
Kiritimati, also called Christmas Island, belongs to Kiribati and lies in the central Pacific. Kiribati moved the International Date Line around its eastern islands in 1994, bringing the country's widely separated islands onto the same calendar date. The change took effect in 1995.
Kiritimati observes Line Islands Time, which is UTC+14. That time-zone position means its local date advances earlier than almost anywhere else on Earth, so its New Year's arrival is often featured in international celebrations and news coverage.
The precise claim should be phrased carefully. Kiribati is among the first countries to enter a new year, rather than necessarily being the only first location under every comparison. Time-zone boundaries, uninhabited islands, and nearby countries can affect how “first” is defined.