New Zealanders are being warned to apply for new passports at least two months before they need them.
And the wait time for an urgently required passport has increased to three days plus delivery.
Current advice from the Department of Internal Affairs (DIA) is that people should allow eight weeks, plus delivery, for a standard passport to be issued.
The extended wait times are being blamed on upgrades to the passport system and increased seasonal demand.
More than 38,000 Kiwis are currently waiting for their essential travel documents, the department says.
Have you been affected by the delays? Share your stories with us at: iwitness@rnz.co.nz
The government target for processing passports is 10 days but the current wait-time guideline is more than a month longer than that.
In February more than 39,000 passports were completed; this almost halved in March due to the beginning of the system upgrades, which stopped new applications from being made.
DIA said the "major system upgrade" was the biggest change to the passport system in over ten years and would stretch into mid-May.
The delays might continue as the new system took time to "bed in", it said.
"In light of that, we are reviewing forecasts of likely demand and output over the next few months."
The department's passport team has been plagued by problems since the pandemic when it reduced its workforce and then faced a surge of applications once borders opened - also leading to wait-time targets being exceeded.
Wait times improved over 2023, with the average processing time for standard passport applications at 17 working days.
Between January and March 2024, the average processing time for standard passport applications was 10 working days.
But in April 2024 the average processing time for standard applications jumped to 26 working days.
The urgent service also increased to three days plus delivery, up from the target of two days, amid greater demand and system upgrades.
However DIA said not all applications were the same and some could go though automatic checks which saw them processed more quickly.
It said average processing times were currently less than six weeks, but the upgrades would create outages where passports could not be processed so it was advising applicants to allow eight weeks, plus delivery.
The approach was "cautious" and "conservative" DIA said, but admitted it might not have adequately warned applicants about the wait times.
It initially said it would be six weeks, plus delivery. After queries from RNZ this advice was changed to eight weeks, plus delivery.
"We anticipate that average processing times will increase over the next month."
DIA said May was usually a big month for applications.
"This seasonal fluctuation, together with the changes to our system have prompted us to be cautious and advise people to allow six weeks, plus delivery, although in many cases we expect to deliver their passports much sooner."
Those who applied before the six-week-wait guidelines were likely to get their new documents within the advertised timeframe at the time of application, but not all.
"One thing to note is that the timeframes we provide are a guideline, not a guarantee," DIA said.
"Reducing passport processing times continues to be one of the department's top priorities, and we are constantly looking for ways to achieve this, even as we work to adapt to our upgraded system.
"We take actions daily to review demand, allocate staff to tasks and enhance productivity.
"Examples on how we do this include analysing our data, identifying where the bottlenecks are and ensuring we have the right amount of staff working in the right areas."
The tech upgrades were set to improve the application process for groups and families and to make the website and processes simpler.
The department said it was working hard to reduce waiting times, but it was encouraging people to allow plenty of time.