New Zealand Rugby has reported a $17 million loss in the 2018 financial year, after its $30m profit the year before, despite recording its second-highest annual revenues of $190m.
Deloitte said in its annual "state of the unions" report, which also tracks the off-field financial performance of the provincial unions, that a decline was "always to be expected" following the British and Irish Lions tour in 2017.
Deloitte said New Zealand Rugby still had a strong financial position to build upon in the upcoming years, with net assets standing at $104m.
New Zealand's five Super Rugby clubs do not publish their financial results, but Deloitte said "anecdotal evidence" suggested they were facing financial pressure with "decreasing gate attendances being well publicised, as well as being observable from game footage".
Deloitte said Super Rugby club shareholders, which include NZ Rugby and provincial rugby clubs, "do need to carefully consider how they invest future resources for the benefit of the Super Rugby clubs given they provide a massive opportunity and pathways for professional players into All Black teams".