Will Tanner is Director of Onward and Guy Miscampbell is Senior Research Fellow at Onward.

It was a false promise but a powerful one. At the 2017 election, Jeremy Corbyn won over a generation of younger voters partly by promising to cancel their student loans. The result was a 35 point lead for Labour amongst 18-24 year olds and a 29 point lead amongst 25-34s. It was the Conservatives worst result amongst younger voters in decades.

The Government’s response to this “youthquake” – an independent review of post-18 education funding, led by Philip Augur – will report next month. But if rumours of its recommendations are true, it will do little to win over a generation of young people who believe that the system is stacked against them. The idea floated in several newspapers of a simple cut in tuition fees to £6,500 is unlikely to make much difference – benefiting only future students and still leaving graduates with high repayment costs as they save for a home, while reducing funding for Britain’s best universities.

The reality is young people are right to think the higher education system doesn’t work for them. Today’s students face some of the highest marginal tax rates in Britain when repayment rates are taken into account. We abolished tax rates of over 50 per cent for people earning over £150,000, but higher rate graduates pay 51 per cent, while those earning above £25,000 facing marginal tax rates of 41 per cent. It is no wonder younger generations are finding it harder to save to get onto the property ladder – leaving them with less wealth and lower rates of property ownership than previous generations, as well as worse pensions.

The standard response to that graduates earn more so it is fair they pay back at a significant rate. But this is only partially true, as Onward’s research shows today. It is true many courses deliver a major earnings premium: a male graduate from LSE can expect to earn, on average £63,220 five years after graduating. But many courses deliver no such premium. In fact, in 40 per cent of graduates studied subjects where their median earnings were so low that after five years they would not reach the £25,000 threshold where they start paying back their loans.

A decade after graduation, one in ten graduates will be earning less than £25,000, according to their course earnings potential, and the most popular subject group, Creative Arts, will deliver an average salary of just £23,200 for the 125,000 students currently studying it. The net result of these weak earnings is that up to a quarter of students are currently studying courses that are not worthwhile for the taxpayer, and a fifth will be no better off than if they had chosen a non-university route, such as an apprenticeship.

For two decades, politicians have been trying to get as many young people to go to university as possible, because they believed that a degree would always deliver higher wages. This was a false promise, with significant implications for the taxpayer. Low graduate wages mean that 83 per cent of student loans will never be paid off in full, leaving a £28 billion hit to the deficit when they are written off in 30 years’ time.

The answer, clearly, is not just to abolish or reduce tuition fees, both of which would only help those who graduate in the future, and could reduce university places as seen in Scotland. Nor is it to introduce a straight graduate tax, which would leave most people paying roughly the same. A better answer, as set out in our report, would be to introduce a graduate tax cut to put money back in the pockets of young people, paid for by reducing the number of wasteful courses that harm graduates’ prospects and cost taxpayers billions.

A graduate “tax cashback” of 50 pence in every pound of loan repayments would halve the monthly repayments of around 2 million graduates currently paying back on their loans. Unlike the alternatives, it would benefit all graduates repaying their loans, now and in the future, and put money help them save for a deposit or contribute to their pension. As we show, the costs could be offset by encouraging a tenth of students away from low-value university and towards higher-value technical education, which have higher earnings despite years of underinvestment.

If the Conservatives are to become a serious force amongst younger voters again, as they were during the 1980s and early 1990s, they must embrace reforms that side with young consumers and young taxpayers – ensuring students are not being ripped off and helping graduates to keep more of their earnings. A tax cut and a crackdown on low value courses would be a good start.