Infometrics currently expects that economic activity was down 12.6 per cent per annum in the June 2020 quarter.
That compares with estimates of a 16 per cent by ANZ and 13 per cent forecast by Westpac.
The official GDP numbers for the June quarter are due on September 17.
"The June 2020 quarter likely represents the largest single hit to the New Zealand economy on record, but the economic scarring and restructuring will continue to occur over the coming years," Olsen said.
However, economists are also expecting a significant bounce back in activity through the current third quarter.
"Not all regions have felt the economic effects of the pandemic equally," Olsen said.
The Otago region saw the hardest hit to economic activity, with a 15.6 per cent per annum drop, as the collapse in tourism activity hit a number of local economies, the report forecasts.
"Meanwhile, the Manawatū-Whanganui and Gisborne regions weathered the storm as well as could be expected, with economic activity falling by less than 9 per cent per annum.
"The structure of local economies is key to deciphering how the economic hit will reverberate throughout the New Zealand economy" Olsen said.
"Regional economies have taken a battering from the pandemic, but local leaders, businesses, and communities have shown incredible resilience to get their local areas moving ahead."