Government spending on adult education and apprenticeships in England will be 25% lower in 2025 than in 2010, despite the extra £900m promised in last year’s spending review, according to the Institute for Fiscal Studies.

The IFS calculated that the additional funding only partially reverses the 38% fall in overall spending on adult education and apprenticeships over the decade since 2010-11, when the Conservatives entered government, due to austerity and inflation.

“This will make it harder to achieve the government’s high ambitions to improve technical education and adult skills in order to level up poorer areas of the country,” the IFS said, ahead of a new report, Adult education: making it a genuine second chance, published on Monday.

The report found that while there have been increases in the numbers taking more advanced qualifications, such as higher apprenticeships and degrees, the numbers of adults taking more basic qualifications has fallen steeply since 2010-11 – including a 50% fall in those taking qualifications at GCSE level and below.

In November’s spending review, the chancellor, Rishi Sunak, stated that “total spending on skills will increase over the parliament by £3.8bn by 2024-25”, equivalent to a 26% increase in real terms compared with five years earlier. But the IFS found that only £900m was additional spending. “Given the size of past cuts, however, this will only bring total spending on adult education and apprenticeships back to around 2015 levels,” it noted.

Imran Tahir, an IFS research economist and one of the report’s authors, said the government’s plans will provide extra help to those who left schools with good GCSEs or equivalent qualifications.

“Yet the main plans set out for helping adults with few qualifications – skills bootcamps and the new [numeracy] programme – are relatively untested and are unlikely to lead to formal qualifications. Providing effective support and training for this group is a significant challenge that will be key to levelling up poorer areas of the country,” Tahir said.

The IFS found that in 2011-12, there were more than 3 million “low level” adult learners taking classroom-based qualifications, but by 2019-20 that number had more than halved. The biggest fall was in adults taking courses below GCSE level.

There has also been a decline in the numbers of adults starting apprenticeships, especially since the introduction of the apprenticeship levy on larger firms in 2017. “As a result, there was little chance of meeting a government target of 3 million new apprenticeship starts between 2015 and 2020,” the report states.

The report, funded by the Nuffield Foundation, praised the new lifelong loan entitlement being introduced by the government as “a sensible move” that effectively extends the funding system used for higher education to a number of further education courses.

But it warns that the four-year entitlement for loans is “substantially more restrictive” than the current system of funding, and risks “achieving precisely the opposite of the government’s stated aim by making it harder for people to retrain later in life”.

Toby Perkins, Labour’s shadow minister for further education and skills, said: “The government’s neglect of further education is plain to see in shrinking opportunities and falling numbers of adults taking part in training and reskilling.

“Together with the lowest level of workplace learning in over a generation, it is clear that the Conservatives do not have a plan to tackle skills shortages across our economy.”