Queenstown skydiving instructor Jason Mullins who has been a New Zealand resident for 10 years is frustrated with the whole process of becoming a New Zealand citizen.

A skydiving instructor who has waited a year-and-a-half for citizenship says it has taken some of the gloss off the milestone event for him.

More than 26,000 residents are waiting to be New Zealanders, but while some are processed in a week others are finding themselves in the dark about their applications.

Queenstown dad Jason Mullins, 42, is annoyed an automated 'presence calculator' showed he was eligible to apply, and he found out only last month that his time overseas should have meant he needed to apply three weeks later than he did.

"What I'd like to know is this still does not answer why it's taken 18 months to get a case officer.

"I am so frustrated with the whole situation. It's taken the excitement away of becoming a New Zealand citizen.

"I've been in New Zealand more than 15 years now and a resident for 10 years.

"My partner can apply in a month and she's been in the country for six years so potentially she might get it before me.

"My son is the only one with a kiwi passport. I've been waiting so long and I have a lot of friends who haven't even been in New Zealand that long and they've all got it now."

If he had been told at the time the presence calculator had made a mistake he could have applied 23 days later and would be a citizen by now, he says.

The calculator searches Immigration New Zealand to check residents have spent enough time in the country in the previous five years.

Auckland Saran Anandan, a disability support worker, has been waiting less time but has been told he can get no update until he too has been waiting for 18 months.

"No communication, nothing. When we reach them, they simply say you have to wait 18 months so don't call us before then. It's like a mystery process."

He wants to know what plan there is to get rid of the backlog.

Rory Kinahan, from Canterbury, says he heard nothing after applying nine months ago.

"I've been in the country legally for over 35 years, have never been anything but an exemplary citizen, have lived with my wife for 20 years in New Zealand and have two almost adult Kiwi children who were born here.

"I have no idea whatsoever where I am in the queue or when I will finally receive my citizenship.

"Is this acceptable? Why, given the amount of time they've had to improve their system, are waiting times only getting longer?

"Perhaps Internal Affairs should consider hiring a third party firm to handle the Citizenship Office.

"If it was a private company it would have gone bust or been rapidly improved several years ago."

Internal Affairs general manager of services and access Adrian Jarvis says the average time for all applications on hand, including applications that had been assigned to a case officer, the ones on hold and those waiting for manual assessment, was between eight and nine months.

"The shortest waiting time, for applications which meet all automated checks and are being allocated to officers to make the remaining manual checks, is seven working days," he says.

"Reducing the decision timeframes on citizenship applications continues to be a priority for the Department.

"We are taking several measures to achieve this, including the recruitment and training of staff and investing in technology changes to speed things up.

"However, our first obligation is to ensure the application meets all of the requirements under the Citizenship Act."

- RNZ/ Gill Bonnett