South Belfast has the joint-lowest percentage of constituents re-joining the electoral register across the North.
The constituency, formally known as Belfast South, joins Foyle as the lowest ranked of 18 constituencies, with just 81 per cent of the eligible electorate re-registering to vote.
Every ten years, the electoral register is wiped as part of a legally-required canvass. Everyone in the North is required to re-register to vote, even if they have been registered previously.
The Electoral Office was set to carry out a review last year, but its plans were delayed due to the Covid-19 pandemic.
In 2016, more than 60,000 voters were removed from the register ahead of the 2017 Assembly Election.
The Electoral Office said those who had been removed had failed to return an electoral registration form during a canvass of electors in 2013.
Across the North, 85 per cent of people have responded to the latest canvass.
The highest response rates are in South Antrim (87 per cent), Strangford (87 per cent) and Lagan Valley (88 per cent).
Cahir Hughes, Head of the Electoral Commission Northern Ireland, said: “Securing your place on the electoral register protects your democratic right to vote and ensures that you can have your say in elections.
“The canvass is an opportunity to confirm your details on the register are accurate. Everyone must respond, even if you were registered before.”
Registration can be completed online in five minutes at gov.uk/register-to-vote.
The next Assembly Election is scheduled to take place in May 2022.