Up to 75 per cent of retailers have online channels and will be able to take advantage of a lifting of restrictions, which could come next week.
Retail NZ says that the remainder would find it tough.
"There'll be a real challenge for the remaining 25 per cent to look at putting in place either online sales or telephone orders, and for some businesses, especially cafes etc, it may not be practical," said Retail NZ chief executive Greg Harford.
Overall the announcement of details of more relaxed rules was good news for the economy.
"Retail NZ has been advocating for the e-commerce and click and collect services to be allowed, providing that they can be done safely, and it is good news for consumers, retailers and the economy as a whole that these will be permitted when New Zealand eventually moves to level 3 restrictions," said Harford.
The retail sector has been battered by the coronavirus crisis and most physical stores, including malls, will remain closed under alert level 3. Cabinet will make a call on moving to that level on Monday.
The retail sector was focused on domestic consumption and could play a key role in helping reboot the New Zealand economy, said Harford.
"Online trading, and the provision of click and collect services are a key means by which we can start getting things going again. Retailers are now in a position where they can begin planning for a level 3 world, with greater clarity around what is permitted."
He said businesses would now be thinking about how to manage social distancing and hygiene requirements in workplaces, making sure they have online fulfilment organised to meet customer needs, and establishing an online presence if they don't already have one.
"There are situations where a broader range of physical stores could be operated safely, but the Government has not yet moved to permit this to happen. Retail NZ will continue to be discussing these issues with Government over the coming weeks."
Last month Retail NZ estimated that up to 10,000 retail workers could lose their jobs over the next few months as retailers big and small grappled with disruption from Covid-19.
Chris Wilkinson, managing director of First Retail Group, said he did not believe the outbreak would kill off the sector, but he said it would "flatten spending" for a while.
He anticipated that the drop in spending would rebound "once the immediate danger is past and confidence returns" among consumers.