Geor said the price increase was necessary to help cover the cost of delivering letters and to ensure NZ Post can sustain the current level of postal service.
"We continue to work hard to keep the cost of posting mail as low as possible, by significantly reducing our network costs and making big changes to how we operate," said Geor.
"However, with an annual decline of approximately 60 million mail items through our network, we also need to increase the price of postage."
Geor acknowledged the price increase would have an impact on existing customers.
"We want to reassure them we are working very hard to ensure our mail business is fit for the future, and that the changes will not affect our delivery service."
NZ Post made a $7 million profit in the six months to December 31 up from $6 million in the same prior period.