"It's demand and it's the unplanned absences around Omicron. At times over the last couple of months, we've had 40 per cent of our staff absent due to either being unwell themselves or looking after family members or having to isolate, and when you're a production organisation like ours, that has a massive impact on your ability to serve your customer."
For peace of mind, people should allow five to six weeks, she said.
"The demand that we've got at the moment is not unprecedented. We're talking about 30,000 to 35,000, maybe 40,000 passports in a month.
"At our peak, well before Omicron, well before Covid, well before borders, and all of that stuff, in sort of March 2019, we were issuing 60,000 passports in a month.
"But our workforce looked very different and it was built around that kind of demand level."
They had to rapidly shift their workforce when Covid-19 cut demand - at one stage down to 13 per cent the number they would usually issue - and then ramp back up when the borders started to reopen, she said.
Robertson recommended travellers check any passport expiry requirements of the country they plan to visit and whether their passports had the necessary amount of time before their expiry date.
People could apply to renew their passport online and didn't need a RealMe account to start an application, she said, and that included people who were overseas.
For those who needed travel documents in an emergency, a passport could be delivered within three days.
"We're certainly seeing a lot of people who are finding themselves in that position but thankfully we still have that urgent service running as it's intended."
Internal Affairs hoped to have the wait for a passport renewal reduced within 10 days by July this year, she said.
It wasn't only passports that people needed to consider. Robertson said people should ensure they researched any vaccine pass requirements for any travel they planned to do overseas.
