Learner drivers are having difficulty booking tests this year because of the backlog caused by coronavirus.
A rapid decline in driving instructors and baby booms around 17 years ago are also being blamed for the delays, with a report by learner driver insurers Marmalade saying they don't expect it to improve until January 2024.
Some learner drivers in Cardiff trying to book a test now can't find any dates left this year and fear they will have to wait until 2023 to get a date.
Others are being forced to travel for miles to test centres that are offering available slots.
Read more: DVLA backlog sees nearly a million drivers hit by licence processing delays
The Driver and Vehicle Standards Agency (DVSA) warns that learners should only take their test when they are "confident" they will pass as around half of candidates are failing.
It's been estimated that more than three million learners will be impacted by the backlog over 2022 and 2023 which won't fully ease until January 2024.
In 2022 demand has reached its peak with over 520,00 learners piled in a backlog - making it impossible for thousands to get a test booked.
Data by Marmalade shows that overall more than three million learners are expected to battle for test slots in 2022/23, with some securing tests in time and others falling into a rollover.
The backlog estimation comes after Marmalade obtained data through a Freedom of Information request showing all tests booked for 2022, as well as gross demand for tests through the DVSA across all of 2021.
As well as this, after analysing Office for National Statistics 2021 driving test data, the team were able to establish an average capacity for practical testing across the UK.
It’s predicted that across 2022 and 2023, demand for tests will soar to 3,261,469 across the UK, far higher than what the DVSA is estimated to accommodate in its monthly testing.
Capacity only becomes available from January 2024 onwards, which means another two years of delays, extra costs and frustration for thousands of learners across the UK.
One mum, from Cardiff, whose son turned 17 in February and can't get a test until next year said: "He got his theory test this week, but I was shocked when I went book the test and we couldn't find any slots at all this year.
"It is crazy. You can't keeping having lessons for the next year as they are expensive as it is, but they will still need to be ready when the time does actually come."
The Marmalade research found that on average, learners in the backlog will purchase eight extra lessons in a need to remain test ready - at an average of £31.15 per lesson, that’s an added expense of £249.20 for every learner.
DVSA chief executive, Loveday Ryder said: "We are doing all we can to provide as many tests as possible so we can get our services back to normal. I know learners will be keen to take their test now, but it is important that they are properly prepared for their test and don’t take it before they are ready.
“With more than half of candidates failing, and demand currently extremely high for tests, learners should only take their test only when they are confident they can pass. This will help them to avoid a lengthy wait for a retest and help us by not adding to the driving test waiting list.”
They say plans to cut the backlog include offering overtime to examiners, inviting recently retired examiners back to conduct tests and launching a campaign to recruit an additional 300 examiners.
Crispin Moger, CEO of Marmalade said: "Our recent survey of learner drivers across the UK found that 77% of learners cite the extra cost of more lessons as the biggest frustration in the delay for tests, followed by delaying independence and freedom (68%) among others.
"With this in mind we’d encourage learners to forward plan as much as they can, also considering private practice with a family member to supplement lessons to help ensure they are ready when the big day comes."
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