Governor-General Dame Cindy Kiro has formally issued the writ for the Hamilton West by-election, kick-starting the formalities.
Candidate nominations will close at noon next Tuesday at noon and the list of candidates will be announced the next day.
The seat is vacant because of the resignation of former Labour MP Gaurav Sharma, who intends to re-contest it as an independent candidate.
Labour and the Opportunities Party have already announced their candidates, and National will choose from its shortlist of three on Sunday.
Today also marks the close of the Hamilton West electoral roll for printing. Anyone enrolling or updating their details after today will need to cast a special vote.
Eligible voters can enrol or update their details online at vote.nz/enrol or enrol and vote at a voting place when voting begins on 28 November.
The by-election will be held on Saturday, 10 December.