"At NZ Rugby we are forecasting up to a 70% decline in revenue," she told reporters.
"We have had to quickly adjust our cost base accordingly."
The shutdown to contain the coronavirus has frozen all rugby in New Zealand, idling hundreds of staff and players in the country's five teams that compete in Super Rugby along with sides from Australia, South Africa, Argentina and Japan.
The All Blacks' two-test series against Wales and one-off test against Scotland scheduled in July are also expected to be postponed or cancelled, which would deliver a further hit to NZR's finances.
NZR's gloomy revenue forecast came after reporting a better-than-expected NZ$7.4 million ($4.53 million) loss in 2019.
With 2019 a World Cup year, NZR had budgeted for an NZ$11.8 million loss from a reduced international programme but said strong results from sponsorship and licensing had helped mitigate the damage.
Revenue of NZ$187 million in 2019 was down 1% on the previous year but represented a 40% increase compared to the previous World Cup year in 2015.
"When you consider the significant impact on broadcasting and match day revenue in a Rugby World Cup year due to a condensed international programme, the commercial income from sponsorship and licensing has been a real success story,” Nicol said.
She added that cash reserves of NZ$93 million had been a vital buffer in a year where there had been a "massive shock" to revenue.
New Zealand, which has recorded over 1,400 COVID-19 infections and 19 deaths, eased a strict month-long lockdown on Tuesday, allowing some 400,000 people to return to work.
Sports remain frozen, however, and NZR Chief Executive Mark Robinson said the governing body was working with authorities to make sure rugby could "get back on the field as soon as possible."