Locals are being sent voting papers for the first postal referendum on a new national flag.

Voters are being asked to rank the five final options for a flag, according to their preference.

The Electoral Commission expects to announce the results in mid-December.

Voting is open for three weeks, finishing on December the 11th.

The most popular flag design will then be the subject of a second referendum in March.

That's when voters will be asked to choose between the top alternative design and the current flag.

It's the first time in New Zealand's history that residents have been invited to choose a national flag.