The new lockdown measures will cost the economy about $440 million per week - or 0.15 per cent of annual GDP, according to estimates by the ASB economics team.
"Our estimates suggest a modest impact on New Zealand's GDP, but this could easily grow," ASB senior economist Mark Smith said.
"The more severe and long-lasting the outbreak, and the more difficult to contain it, the larger the subsequent economic disruption and likely cost."
ASB has modelled a range of costs based on different alert levels.
They range from a weekly economic cost of $1.6 billion (or 0.54 per cent of GDP) if the whole country went back in to level 4 lockdown, to $166m (or 0.06 per cent of GDP) per week with the whole country at level 2.
The return to higher alert levels would have uneven impacts throughout the economy, Smith said.
"New Zealand was operating at about 95 per cent of capacity at level 1, with the shift to alert level 2 and 3 seeing capacity utilisation fall to anywhere from 80 per cent to 92 per cent of economy wide capacity."
Sectors that would be particularly affected by a shift back up alert levels included accommodation and food services.
Auckland was just one of 16 major regions in NZ, but it carried significant economic weight, he said.
According to official estimates, Auckland accounts for broadly 38 per cent of NZ's GDP and around 33 per cent of employment and one-third of nationwide population.
Brad Olsen, senior economist at Infometrics, said that the restrictions placed on Auckland would disrupt much of its workforce.
"By our estimate, around about 28 per cent of Auckland's workforce cannot operate under level 3, that's about 250,000 jobs. We're likely to see that number of people not operating," Olsen said.
Based on the spending patterns seen across New Zealand the last time the country was under alert level 3 "you're looking at around $60 to $69 million less being spent over the next three days alone [in Auckland] under the level 3 lockdown," Olsen added.
Independent economist Cameron Bagrie said the latest restrictions - which he doubted would only be in place this week - showed parts of the country might have brushed off the impact of Covid-19 too quickly.
"There was a mismatch between the reality and the risks versus the way people were behaving over June and July," Bagrie said, with figures showing a major pick-up in spending and a resilient housing market, suggesting consumer confidence had bounced back.
"There was a little bit more euphoria than was justified by the risk profile that this thing could come back, so that fact that this thing has come back, I think, is a big wake-up call for a lot of people."
While the economy had shown signs it was picking up quickly, Bagrie said, coming out of lockdown, Auckland was showing signs it was behind the rest of the country.
"We were in this recovery sweet spot, the bounce after the first lockdown, but the laggard was actually Auckland.
"Job [advertisements] in Auckland were still well off the pace [of pre-lockdown]. We were seeing a big rise in the number of commercial leases that were coming on the market, in Auckland, as companies gave up space as their workers opted to work from home, or companies shed staff."
Bagrie said while many companies had managed to cope with the first lockdown, it was unclear whether they would have the financial capacity to cope with another.
But another independent economist, Tony Alexander, said he felt businesses were better prepared to cope with new lockdown rules than they were in March.
"The impact on our economy and businesses this time around won't be anywhere near as severe as from late-March into May," Alexander said.
"There is no new impact on international tourism or export education. There is no new shock to the world economy and downside export price risk. In fact, a lower New Zealand dollar will help our exporters."
There would be no new tightening of bank lending policies as they already reflected the risk of this happening, he argued.
"The impact [so far] is of limited spread and duration - but we await to see test results in the next three days. This is not a level 4 shutdown, and most office-located businesses can switch to working from home immediately with minimal if any business flow interruption."
ASB's Smith agreed: "While it may feel like we are back to square one, the lockdown in March provided us with a crash course in doing things differently."
"New Zealanders and businesses have learnt a lot from the previous lockdown experiences and should be more resilient to this latest wave."
That would particularly be the case for businesses outside Auckland, which were still able to operate, albeit with distancing restrictions.
"The New Zealand economy is in a weaker position than it was pre-Covid-19. A considerable amount of policy ammunition has already been spent, Smith said. "Let's hope our earlier lockdown experience has taught us a thing or two about adaptability."
- Additional reporting Hamish Rutherford