Student Loan Interest Rates Explained
UK student loan interest is linked to inflation, specifically the Retail Prices Index (RPI), and the exact rate depends on your plan. On some plans everyone pays the same RPI-linked rate; on others, higher earners pay RPI plus an extra percentage while lower earners pay less. But here is the crucial point most guides bury: for a great many borrowers, the interest rate barely matters. Because your repayments are fixed at 9% of your income above the threshold, and any balance is written off after 25 to 40 years, the interest rate often changes only how big a balance eventually gets cancelled — not what you actually pay each month.
This guide explains how the rates are set, how they differ by plan, and why you probably do not need to lose sleep over the headline figure.
At a glance
- Linked to
- RPI (Retail Prices Index) inflation
Key Takeaways
- Student loan interest is RPI-linked, and the precise rate depends on your plan type — some plans add a margin on top of RPI for higher earners.
- Interest changes your balance, but your monthly repayment is fixed at 9% of income above the threshold, so a higher rate does not raise what you pay.
- Because most borrowers never repay in full before write-off, the interest rate is often academic — it only affects the size of the balance that gets cancelled.
- The interest rate only really matters if you are a high earner on track to repay your loan in full before it is written off.
How the interest rate is set
Student loan interest in the UK is pegged to RPI, a measure of inflation, usually taken from a specific month each year. Depending on your plan, the rate is either RPI on its own or RPI plus an additional margin.
The government also applies caps in some circumstances, so the rate charged does not run far ahead of comparable market interest rates. That is why the rate can change each year and even during the year, and why the figure you see quoted may differ from what you are actually charged. Always confirm your current rate by logging in at gov.uk.
How interest differs by plan
The rules vary by plan:
- Plan 1: interest is typically the lower of RPI or a rate linked to base rates, so it tends to be modest and simple — the same for everyone on the plan.
- Plan 2: interest is income-linked. While studying and for higher earners it can be RPI plus up to an additional percentage, tapering down towards RPI-only for lower earners.
- Plan 4 (Scotland): interest is usually RPI-based, similar in spirit to Plan 1.
- Plan 5: interest is set at RPI for most borrowers, without the income-linked margin that Plan 2 applies.
- Postgraduate Loan: interest is typically RPI plus an additional percentage.
For how the plans differ more broadly, see Plan 1 vs Plan 2 student loan and Plan 5 student loan explained.
Why the headline rate often doesn't matter
This is the part that surprises people. Your repayment is not affected by your interest rate at all. On most plans you repay 9% of your income above the threshold, and that figure is set purely by your salary. Whether your loan is charging 4% or 8%, your monthly deduction is identical.
Interest only changes your balance. And your balance only matters if you are going to repay it in full before write-off. For the large share of borrowers who reach write-off with a balance still outstanding — particularly on Plan 5 with its 40-year term — a higher interest rate simply means a bigger balance gets cancelled for free at the end. You never feel it.
That is why chasing news headlines about student loan interest rate rises can be misleading. For most borrowers, a rate rise does not cost them a penny more, because they were never going to clear the balance anyway. See when is a student loan written off for the write-off periods.
When interest genuinely matters
The interest rate does matter if you are a high earner on track to repay in full before write-off. In that case, you will actually pay the accumulated interest, so a higher rate increases your total cost. For these borrowers — and only these borrowers — it can occasionally be worth considering overpayments if the loan's rate exceeds what they could safely earn on savings. We work through this in should I pay off my student loan early.
If you are unsure whether you fall into this group, the test is simple: will your repayments over the years until write-off add up to more than your balance plus interest? If not, the rate is largely irrelevant to you.
What you should actually do
For most people, the sensible response to student loan interest is to note it and move on. Keep the 9%-of-income mechanic front of mind, understand your write-off date, and use a repayment estimate to see your real monthly cost — our student loan repayment explained pillar guide includes a calculator. Focus your financial energy on things that genuinely move your position, like your pension, savings and, if you are buying, your mortgage affordability.
Frequently asked questions
Why does my student loan interest look so high?
Student loan interest is linked to RPI inflation, and on some plans a margin is added on top for higher earners, which can make the rate look steep. But because your repayments are fixed at 9% of income above the threshold, a high rate usually does not increase what you actually pay each month.
Does a higher interest rate mean I pay more each month?
No. Your monthly repayment is set by your income, not your interest rate or balance. A higher rate increases your outstanding balance, but it does not change your deduction. It only costs you more if you are on track to repay the loan in full before it is written off.
How do I find out my current student loan interest rate?
Log into your student loan account at gov.uk, where your current rate is shown. The rate changes periodically because it is tied to RPI and, on some plans, your income, so the figure quoted in the news may not be exactly what you are charged.
Should I worry about student loan interest rate rises in the news?
For most borrowers, no. If you are unlikely to repay your loan in full before write-off, a rate rise simply means a larger balance is cancelled at the end — it does not increase your repayments. Only high earners set to clear the loan in full are genuinely affected.
General information only, not financial advice. Check your plan type and balance at gov.uk.
