Analysis · IFS | Institute for Fiscal Studies · 7 April 2026
Immediate response to the announcement of a 6% cap on student loan interest rates: What It Means for Your Student Loan
Written by Zubair Arshed FIA, Chartered Actuary
Fellow of the Institute and Faculty of Actuaries
Actuarial Post Life and Health Actuary of the Year 2024
The Institute for Fiscal Studies has responded to an announced 6% cap on student loan interest rates. On the surface a lower interest rate looks like a straightforward win, but the mechanics of the repayment system mean the cap matters far less than the headline suggests for most people who will never clear their balance before write-off.
This analysis responds to reporting by IFS | Institute for Fiscal Studies. We recommend reading the original alongside it: Immediate response to the announcement of a 6% cap on student loan interest rates ↗
What has actually been announced?
The development here is a proposed cap that would stop student loan interest rising above 6% a year. The IFS has published an immediate response, which is the kind of rapid technical assessment they issue when a government sets out a change to loan terms. I only have the headline in front of me, so I am analysing the cap itself and how it interacts with the existing rules rather than attributing specific numbers to their write-up.
An interest cap does one thing: it prevents the rate charged on your outstanding balance from exceeding a set ceiling. To understand who this helps, you first need to know which plans can charge more than 6% in the first place. Plan 5 (the current system for English students who started from 2023) charges RPI only, so it would only be capped in a year when RPI itself climbs above 6%. Plan 2 charges RPI plus a sliding scale up to 3% for higher earners, and postgraduate loans charge RPI plus 3% flat. Those are the plans where a 6% cap can actually bite.
A cap is genuinely useful in one respect: it protects you against a spike in inflation. When RPI ran hot in 2022 and 2023, headline student loan rates briefly threatened double digits, and emergency caps were applied. Baking a permanent ceiling into the rules removes that anxiety. Whether it changes what you actually repay is a separate question, and that is where the IFS tends to focus.
Does a lower interest rate really cut what you repay?
Here is the point that surprises most graduates. Under the income-contingent system, you repay 9% of everything you earn above your threshold (6% for postgraduate loans), regardless of the interest rate. Your monthly repayment is driven entirely by your salary, not by your balance. The interest rate only changes the size of the debt, not the size of your payments.
That distinction matters because most borrowers on the longer plans never repay their loan in full before it is written off. Plan 5 loans are written off after 40 years, Plan 2 after 30 years, and postgraduate loans after 30 years. If your balance is going to be cancelled anyway, cutting the interest rate simply reduces a number on paper that you were never going to pay off. The cap is cosmetic for you.
The cap does real work for one group: people who will clear their loan. High earners, or those with smaller balances relative to income, pay off everything they borrowed plus interest before the write-off date. For them, a lower rate genuinely reduces the total handed over. Everyone else feels no difference in their monthly deductions and no difference in their lifetime cost, because write-off arrives first either way.
How does the cap affect each plan and borrower?
Take a postgraduate borrower, since that loan charges RPI plus 3% and repays at 6% above a £21,000 threshold. Imagine you earn £41,000 with a £30,000 balance. Your repayment is 6% of the £20,000 above the threshold, which is £1,200 a year. If RPI were 4%, your rate would be 7%, generating £2,100 of interest on that balance. A 6% cap trims the interest to £1,800, saving £300 in that year. Notice your repayment stays £1,200 regardless, and it does not even cover the interest, so the balance keeps growing towards write-off at 30 years. The £300 saving is real but it never reaches your pocket unless you were on track to clear the debt.
For Plan 2, remember the £29,385 threshold is frozen until at least April 2030, and the top RPI plus 3% rate only applies once you earn above £52,884. A cap protects the highest earners in a high-inflation year, which is precisely the group most likely to repay in full, so this is where the cap delivers the most tangible benefit. Middle earners heading for write-off see little change.
Plan 5 borrowers are affected least of all. With interest set at RPI only, the cap does nothing unless inflation exceeds 6%, and over a 40-year term almost all Plan 5 borrowers are expected to reach write-off without repaying in full. Plan 1 already caps interest at the lower of RPI or Bank Rate plus 1%, so a separate 6% ceiling would rarely be the binding constraint. If you want to see whether the cap touches your own numbers, you can model your salary, balance and plan in the StudentLoanCurve calculator and watch how little the monthly figure moves.
What is the likely future impact?
For a typical Plan 2 or Plan 5 borrower heading for write-off, the 6% cap will change lifetime repayments by close to nothing, because monthly payments track income, not interest. For a high earner or someone with a small balance who clears their loan, capping a 7% rate at 6% could save several hundred pounds a year in a high-inflation period: roughly £300 on a £30,000 balance for each percentage point trimmed.
The mechanics are certain: repayments depend on income and write-off applies regardless of rate, so the muted effect for most borrowers is not in doubt. The uncertainty sits in the announcement itself. I have only the headline, the precise design and start date of the cap are not confirmed to me, and future inflation determines how often 6% actually binds. Government has revised loan terms before, so treat the detail as provisional.
See what this means for your own loan
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