A 'good' business day is defined as a day on which banks in New Zealand are generally open for business, or a day other than one on which banks in New Zealand are obliged or permitted to close - specifically excluding Saturday and Sunday.
Essentially, good business days are weekdays (Monday to Friday) other than public holidays.
With respect to the calculation and publishing of NZdata reference rates, where these public holidays occur on a standard business day (Monday to Friday), NO reference rates are published.
Exception – BKBM rates (NZ Bank Bills) are calculated and published on both Wellington and Auckland Anniversary Days
If a public holiday falls on a Saturday or Sunday, then the public holiday is moved to the Monday (or in some cases Tuesday) and is known as ‘mondayisation’.
The Friday before and the Monday after Easter Sunday are public holidays in New Zealand.
Easter Sunday falls on the first Sunday after the full Moon date (which is based on mathematical calculations), that falls on or after March 21. If the full Moon is on a Sunday, Easter is celebrated on the following Sunday.
These Include:
The observed dates for these will be the closest Monday.
Matariki is both the name of the Pleiades star cluster and of the celebration of its first rising in late June or early July. While the start of Matariki shifts from year to year, the New Zealand Government has stated that it will always fall on a Friday and have released the dates that this holiday will fall on until the year 2052.
NZFMA Data - Calendar (nzdata.org) contains a list of holidays for the next 12 months.
A comprehensive list of holiday dates, both actual and observed, for the years 2021 through to 2052 is available here.
In general, the NZFMA recommends that transactions should not be negotiated for settlement or price fixing (rollover) on a non-business day (see below for non-business days in New Zealand). Other conventions can be utilised, if agreed upon at the time of dealing.