Dunedin Taxis chairman Tony Ross said this week drivers needed to know they would not have to wait an unreasonable time for their passenger endorsements to be renewed.
At least three Dunedin drivers were affected by processing delays which could have stopped them working.
"We have emphasised to our people to get their applications in early because there will be delays, but the delays have been going on for far too long," Mr Ross said.
"We need to know that applications will be processed in good time, so that drivers will have the licence they need to do their job.
"It shouldn't be taking as long as it has."
The New Zealand Taxi Federation has complained to the New Zealand Transport Agency (NZTA) about delays in renewing and approving passenger licence endorsements.
The advertised timeframe was eight weeks, but there were reports of drivers still waiting 10 weeks after they had made their application.
Federation executive director Tim Reddish said the "diabolical" delays started last year.
At their worst, they might have affected up to 70 drivers nationally over a four- to five-month period, from about 550 applications processed each week.
Mr Reddish and Bus and Coach Association chief executive Raewyn Blakely acknowledged problems had eased over the past six weeks - Ms Blakely said the average wait had been reduced to near 20 working days - but both said the improvement had to be sustained.
NZTA registry and revenue manager Brett Dooley said in a statement it took, on average, eight weeks to process endorsements when the Transport Registry Centre was moved to Palmerston North late last year.
NZTA accepted that was too long, and it had since invested considerable effort improving processes to the point that most applications were processed within 20 days.
It was a significant improvement, he said.
Mr Dooley said some applications took longer, particularly when applicants were requested to provide more information to support them.
Customers should contact the centre if they had any concerns.
In the meantime, Mr Ross said Dunedin Taxi drivers were advised to apply at least three months before their endorsement lapsed, to try and overcome possible delays.
"We've had to be prepared, but it's probably time for NZTA to come up with a definite timetable for processing applications, so we know what we are dealing with before it becomes a problem."
Southern Taxis co-owner Maureen Grant and Otago Taxis manager Katherine Ritchie, both of Dunedin, said drivers knew the risk of not applying earlier than the advertised timeframe.
Mrs Grant noted some drivers got their endorsements back within four weeks, while others waited much longer.
