Why do UK student loans often appear impossible to repay? The reason is not simply the size of the debt, but the way the system is designed. In practice the UK student loan functions less like a conventional loan and more like a graduate tax, except that the tax stops once the loan and interest have been fully repaid.
Students in England can usually borrow two types of loans while at university. The first is a tuition fee loan, which pays the university directly. The tuition fee cap for domestic students in England is currently £9,535 per year. The second is a maintenance loan, paid directly to the student to cover rent, food, transport or other living costs. Students can spend this money as they wish. Because the maintenance loan is substantial, the total amount borrowed over three years often exceeds £50,000.
The key feature of the system is income-contingent repayment. Graduates only begin repaying once their income exceeds a certain threshold. For those who started university between 2012 and 2022, this is known as Plan 2. The repayment threshold in 2025 is £27,295, and the government has announced that it will rise to £28,470 from April 2025. Graduates repay 9 percent of income above this threshold. If earnings fall below the threshold, no repayment is required.
The amount repaid therefore depends on income rather than the total debt. Suppose a graduate earns £38,470 a year. With a threshold of £28,470, the income above the threshold is £10,000, meaning annual repayments of £900, or about £75 per month. Whether the outstanding loan is £40,000 or £70,000 does not change the repayment that year.
Plan 2 loans also have a time limit. Any remaining balance is written off 30 years after repayments begin. Research by the Institute for Fiscal Studies (IFS) suggests that only about a quarter of borrowers will fully repay their loans under this system. Most borrowers will still have a balance outstanding when the write-off occurs.
The system therefore behaves very much like a graduate tax. Higher earners repay more and are more likely to clear the full balance. Lower earners may repay only part of the loan before the remaining amount is written off by the government. Once the loan and interest have been fully repaid, deductions stop immediately.
Interest rates are also income dependent. Under Plan 2 the rate is based on the Retail Price Index with an additional margin of up to three percentage points. Students are normally charged RPI plus three percent while studying. After graduation the rate varies with income. Only the highest earners pay the maximum RPI plus three percent, while those on lower incomes pay interest closer to RPI alone.
Another less discussed feature is the repayment threshold itself. The system was originally designed so that the threshold would rise with inflation. In practice, however, governments have sometimes frozen the threshold and at other times increased it substantially. As a result, borrowers from different cohorts may face very different effective repayment burdens even under the same scheme. If student loans are effectively a graduate tax, the threshold arguably should be tied to inflation in law rather than adjusted at political discretion.
The UK student loan system also contains several different plans. Plan 1 applies mainly to students who began university before 2012 in England or Wales. Interest rates are generally lower under this plan. Plan 3 covers postgraduate loans, including both master’s and doctoral programmes. Plan 4 applies to students from Scotland and operates similarly to Plan 1 but with a higher repayment threshold.
Students starting university in England from 2023 fall under a new system known as Plan 5. The repayment threshold is lower and the repayment period has been extended to 40 years. Interest is fixed at the rate of inflation, measured by the Retail Price Index, without the additional margin used under Plan 2.
Understanding UK student loans therefore requires looking beyond the headline debt figure. What matters is not the size of the loan but the repayment rules. In practice the system functions like a graduate tax with an upper limit. The real policy question is not whether the debt can be repaid in full, but whether this structure remains a stable and transparent way to share the cost of higher education.
