New Zealand Standard Time zone is 12 hours ahead of Greenwich Mean Time (GMT+12).
The time for the Chatham Islands archipelago, the smallest region of New Zealand, is 45 minutes in advance of New Zealand Standard Time.
New Zealand operates Daylight Saving Time. Note that New Zealand is in the Southern Hemisphere and that "Summer Time" runs from September to April.
New Zealand Standard Time is currently defined in the Time Act 1974 as meaning the 12 hours in advance of Co-ordinated Universal Time. The Department of Internal Affairs administers the Act.