A proposed law change allowing people to enrol to vote on election day could delay the final result by 10 days.
The legislation - which passed its first reading in Parliament yesterday - has prompted outrage from National MP Nick Smith who has previously described the bill as a "stitch-up".
Roughly 19,000 voters had their ballots disallowed on election day in 2017 because they failed to register to vote beforehand.
The Electoral Amendment Bill will allow unregistered voters to sign up on voting day, but will also extend the deadline for a final result from 50 days after the election's start date to 60 days.
"This change is necessary to support the Electoral Commission to manage the introduction of enrolment on election day and provide more time to process the increased numbers of enrolment and update forms before the official count commences," the legislation said.
Speaking in Parliament, National MP Nick Smith decried the delay.
"That is 10 days less in which we have a government," he said.
"That's 10 days more that we have bureaucrats twiddling their thumbs at a cost of tens of millions of dollars each day.
"Why should the formation of government be delayed because people are not meeting their legal requirement to enrol prior to voting day?"
Dr Smith told RNZ Justice Minister Andrew Little had been "sneaky" and was not upfront about the "quite significant" delay.
"It just reinforces the degree to which this government is playing fast and loose with electoral law."
Speaking to reporters, Mr Little said the trade-off was "very clear from the outset".
"It takes longer to finalise the count and therefore pushes out the date of the return of the writ by 10 days.
"That's totally acceptable if we're going to maximise people's participation in our democracy."
In a statement, a spokesperson for the Electoral Commission confirmed the extended deadline would allow more time to check and process the extra enrolments and special votes.
"This would allow another three days before the election to get voting information out to voters and another seven days after the election, if needed, to complete the official count," they said.
"We estimate it could take an additional six days to produce the official results."