Nearly a third of small and medium sized businesses are experiencing a drop in sales since the country moved into the red Covid-19 traffic light setting.
A survey by accounting software firm MYOB also shows more than a quarter have fewer customers going through their doors.
Close to a quarter also felt they would take a significant financial hit as a result of the red light.
MYOB's head of go-to-market Jo Tozer said despite the country not being in lockdown, consumers were taking a cautious approach.
"If you look at what's happened in Australia where businesses have had to close their doors due to a lack of staff or Omicron effects.
"In New Zealand this could leave a third of SME businesses with limited or no cashflow through that period.
"So if you look at that on top of businesses under pressure for an extended period now, we're likely to see this stretch too far for some - how widespread that is, is yet to be seen."
Tozer said while there have been recent positive changes, such as the booster rollout and loosening of border controls, it was not getting easier for many small business operators.
"For two years businesses have struggled, yet adapted where they could in order to keep cash flowing in. Now, we are seeing new restrictions take their toll through limited customers and sales, and this time businesses have fewer options to access government support," she said.
MYOB's survey also found that businesses were running low on stock levels.
"Dealing with supply chain issues can compound the stress SMEs are currently facing - especially when there's little they can do to control the circumstances.
"However, being transparent with customers by communicating clearly and promptly if an issue crops up, and working to find a solution to their needs - such as creating a list of substitutes for popular items or establishing a priority back-order system - could be a good way to help mitigate potential demand issues."