NZ Post has signalled a price increase for sending letters from early 2022 as mail size continues to decrease.
An NZ Post spokesperson said the postal service will "begin transitioning to a commercially sustainable model" for mail delivery.
However, NZ Post said mail size has continued to decline as more people communicate online.
Twenty years ago, NZ Post said the service delivered over 1 billion mail items annually, but a spokesperson said currently about 250 million items are delivered.
Due to this rapid decrease, NZ Post has announced a price increase in sending letters.
"This means that NZ Post will need to increase the price of sending letters by more than usual next year and in the few years following," a spokesperson said.
While the price change has not been set, NZ Post said the new price will be announced in early 2022.
In 2020, $130 million was given to the postal service from the Government. The money would be used over three years as part of a mail Contract for Services to cover projected financial losses from mail
"Post's revenue has fallen substantially but the costs of delivering the service New Zealanders expect have remained the same. The $150 million equity injection, along with the $130m funding for mail services, means we avoid significant cuts to its service and workforce and big price increases for its customers," Kris Faafoi, Minister of Broadcasting said at the time.
An NZ Post spokesperson said this allowed the service to continue delivering at current service level.
"This allowed us to continue to provide nationwide coverage for mail delivery at current service levels and with price increases lower than what they otherwise would have needed to be."