Immigration New Zealand says the actions of a Jetstar staff member who changed a woman's nationality to allow her to enter New Zealand is a serious breach of the rules.
The woman was allowed to board a plane in Melbourne for New Zealand on 27 January last year, despite not having a visa to do so.
Jetstar was fined $6500 in the Christchurch District Court on Thursday.
Immigration New Zealand's acting general manager Sean Driscoll says the fine should send a serious message to the airline and the industry.
Mr Driscoll told Radio New Zealand's Checkpoint programme the pre-screening of passengers allows the service to manage border risks offshore.
"If a person arrives here who is not entitled to come into New Zealand, then we can face a range of consequences - not the least of which is the cost of having to deport someone in some instances."
A spokesperson for the Australian-based airline says it takes its responsibilities regarding immigration very seriously and regrets the error.
The spokesperson described it as an isolated incident and, once the error was reported, Jetstar investigated the matter swiftly.