Erin has been posting about this, but it's official from INZ now:
Note that, as per Section 78 of the Immigration Act 2009 and E3.10 in the operational manual, this extension will only apply to those that are onshore. People holding temporary visas who are offshore will not benefit from this extension; their visas will expire per usual.Epidemic notices
The New Zealand Government’s epidemic management notice relating to immigration matters comes into effect on Thursday 2 April 2020.
Travellers with a temporary (work, student, visitor, interim and limited) visa expiring before 1 April 2020 who are unable to leave New Zealand must apply online for a new visa. An interim visa will be issued.
Travellers with a temporary visa due to expire between 1 April and 9 July 2020 will have their visas extended to late September. Confirmation of extensions will be emailed to all visa holders.
JandM, may want to sticky this? Will answer a lot of people's questions.