New Zealand Post is in the red after losing $35.6 million in the year to the end of June, compared with a profit of $1.3 million the previous year.
The result includes significant costs relating to the Christchurch earthquake, bad debt provisions at KiwiBank, restructuring and a write-down of an Australian business which it sold during the year.
Underlying profit was $41.7 million, compared with $73.6 million a year earlier.
Chief executive Brian Roche says the result is very disappointing, but he's confident of a return to profit next year.
NZ Post is a State-owned enterprise.