The passport service recorded its longest ever average turnaround times of 40 working days for paper and online first-time applications in 2021.
That is according to the Comptroller and Auditor General's Report on the Accounts of the Public Service 2022.
The report found that while the average turnaround time for first-time online applications reduced to 20 working days by September of last year, there was no change in the average turnaround time for paper applications.
The Department of Foreign Affairs told the C&AG that the reasons for the delays in processing passport applications in 2022 included a surge in demand post the easing of Covid-19 related travel restrictions.
The office also saw increased demand from UK residents as a result of Brexit, while insufficient resources in place at the time to deal with the increased demand were also to blame.
The C&AG said that in October 2021, the Department introduced a dedicated phone line for members of the Oireachtas, through which TDs and Senators could obtain a status update on constituents' applications.
"The Department stated that passports are not issued based on representations from politicians, and that the Oireachtas phone line is not a facility for expediting applications out of turn," today's report said.
In 2022, the Passport Service received just under 1.2 million passport applications, an increase of around 21% compared to 2019, which was the previous highest year for applications.
The service issued 1.09 million that year, 16% more than in 2019, before the Covid-19 pandemic.
The report said the cancellation rate for passport applications has increased year on year since 2015, with a significant increase in cancellations between 2019 and 2022 - from 1.5% of all applications received in 2019, to over 7% in 2022.
"Cancelled first time applications accounted for just over one-third of all cancellations in 2015; by 2022, this had increased to over two-thirds of all cancellations," it said.
The report recommends that the Department should introduce a process where the reasons for cancellation or refusal of passport applications are recorded and monitored to identify trends and to address possible shortcomings or difficulties in the application process.
It also stated that the performance metrics included in the service's annual estimates have changed significantly from 2015 to 2023 and subsequent reporting on actual performance has been inconsistent and incomplete over the years.
The C&AG also found that the level of cost efficiency achieved by the Department in providing the passport service is not known.
The report said that between 2015 and 2022, the passport service's direct costs increased by 113%, while the number of passports and foreign birth registrations applied for over the same period increased by 74%, and fee receipts increased by 68%.
The Comptroller recommends that the Department of Foreign Affairs should introduce a written policy which sets out the extent to which fee income generated should cover the passport service's overall costs.