NZST stands for New Zealand Standard Time. It is always UTC+12.
NZST is standard time. While daylight saving time is in effect, the same areas use NZDT (UTC+13) instead.
Right now Auckland uses NZDT (UTC+13), not NZST.
Where NZST is used
New Zealand.
In some of these countries NZST is used only in part of the country or only part of the year.