Around 60,000 voters could miss out on voting in the September General Election after their enrolment update packs were returned marked "gone no address".

Enrolment update packs were sent to 3.15 million enrolled voters at the end of June to check their details were correctly listed on the electoral roll for the September General Election. Voters whose packs are returned to sender are taken off the electoral roll.

"Those voters need to get back on the roll now so their vote will count this election," chief electoral officer, Alicia Wright said.

"If you've moved house, you will need to update your enrolment details online, or fill in a new enrolment form and return it to us."

People can enrol, check and update their details at www.elections.org.nz, pick up an enrolment form at a PostShop, or request a form by calling 0800 36 76 56 or texting their name and address to 3676.

"You can enrol up until midnight on September 22 but not on election day itself, which is September 23. However, the earlier you're enrolled and ready to vote, the better," Ms Wright said.

Voting starts in New Zealand on Monday September 11 when advance voting places open, and goes through until election day on September 23.