Mt Albert residents will head to voting booths next week to have their say on who will represent them in Parliament for the first half of this year.
Thirteen candidates are competing for David Shearer's seat after the former Labour MP and party leader resigned in December to take up a United Nations posting in South Sudan.
Shearer won Mt Albert in 2014 with a majority of 10,656 votes. National got 14,360 party votes in the seat, more than Labour's 10,823 and the Green Party's 8005 votes.
Labour's Jacinda Ardern and Julie Anne Genter of the Green party are the two main contenders. The rest of the candidates represent minor parties or are running as independents.
The National Party is noticeably absent from the contest, after Prime Minister Bill English said his party chose not to put up a candidate because the seat was a sure win for Labour.
New Zealand's newest party The Opportunities Party, headed by multimillionaire economist Gareth Morgan, is contesting the by-election, standing ex-Morgan Foundation staffer Geoff Simmons.
The Electoral Commission has mailed voting packs to the 45,000 people enrolled to vote in the electorate ahead of voting day next Saturday, February 25.
"If you didn't get yours, you need to contact us now to make sure you're enrolled and ready to vote," the commission's chief electoral officer, Alicia Wright said.
The packs include an "EasyVote" card and Wright said voting would be faster and easier for people who brought the card with them.
Four voting stations have been set up for those who want to cast their ballot earlier.
"Anyone enrolled in the electorate can vote in advance, they don't need a reason," Wright said.
People can also enrol at the early voting stations.
Residents will return to the booths to vote again during the general election later this year.
The commission said residents should check whether they are enrolled by visiting www.elections.org.nz or ringing 0800 36 76 56.