Almost 50,000 people are waiting for their new passports to arrive as processing delays reach more than a month.
The Department of Internal Affairs is facing a surge of applications, while the country experiences a migration loss of almost 9000 people in the year to the end of April, amid a global fight for workers and renewed enthusiasm for overseas holidays.
It has 48,000 applications waiting to be processed.
The department's general manager services and access Julia Wootton said the number of monthly passport applications had quadrupled since the start of the year and increased by more than a third between April and May alone.
In January the team was working through about 12,500 applications, increasing each month, to more than 50,000 in May.
Halfway through June, the team had already had over 24,000, said Wootton.
However, Internal Affairs said these numbers were achievable before the pandemic. In 2019 monthly applications ranged between 45,000 and 79,000.
Before the COVID-19 pandemic began its team was prepared to deal with this volume, but the department cut the number of staff in its passport office when the country locked down.
To meet this new surge, Wootton said they had to rebuild their capacity.
"Our teams are working additional hours, we have brought in staff from across the department, and we are recruiting new staff to meet the demand."
Internal Affairs said the usual 10-day wait was now about a month, with further delays for delivery.
"The steep jump in applications, coupled with staff absences due to COVID-19, has meant that it is currently taking us longer than normal to process applications."
However, Wootton said people who paid for priority processing were still able to get urgent applications within three days.
In June the service delivery and operations deputy chief executive said there hadn't been a backlog like this since 1992.
The department said there were some additional variations in passport processing times dependent on how the photos looked, obtaining witness and reference checks and issuing a passport to children for the first time.
RNZ
