The 2017 British and Irish Lions tour will crucial to New Zealand Rugby's finances, underpinning a five-year plan to break even by 2020.
NZR said it recorded a NZ$463,000 (£221,000) loss in 2015, despite the All Blacks becoming the first team to ever to win back-to-back Rugby World Cups.
While that was less than the £450,000 deficit the organisation was expecting, NZR said the figure was set to blow out to £4.7m this year as it ploughs extra funds into provincial unions.
Chairman Brent Impey said the NZR was still in a "favourable financial position" with cash reserves of £28m, but it needed to find ways to generate extra revenue.
"We face a revenue challenge if we hope to continue growing investment in the game," he said.
"We are forecasting losses in four of the five years, with the exception being next year with the British and Irish Lions.
"Our aim is to reach break-even over the period but it is clear already that this will be a big challenge."
The NZR's annual report did not provide a breakdown of projected losses or how much next year's Lions tour is expected to bolster the bottom line.
However, it said last year that demand was set to exceed the composite team's last tour in 2005, when 20,000 travelling fans created a boisterous atmosphere and injected an estimated £65m into the economy.
The Lions have not won a series in New Zealand since 1971 and next year's tourists face a packed 10-match schedule, including three Tests against the All Blacks.