From the first Sunday in October until the third Sunday in March, all of New Zealand changes from Standard Time to Daylight Saving Time. During Daylight Saving Time, all but the Chatham Islands is 13 hours ahead of Coordinated Universal Time (UTC), also known as Greenwich Mean Time (GMT).

The Chatham Islands are always 45 minutes ahead of the main island group. This means that they are 13 hours 45 minutes ahead of UTC during Daylight Saving Time.

From the third Sunday in March until the first Sunday in October, most of New Zealand follows New Zealand Standard Time. During Standard Time, all of New Zealand, apart from the Chatham Islands, is 12 hours ahead of Coordinated Universal Time (UTC), also known as Greenwich Mean Time (GMT).

The Chatham Islands are always 45 minutes ahead of the main island group. This means that they are 12 hours 45 minutes ahead of UTC during Standard Time.