Student Loan Interest Rates Explained
Understanding how interest is calculated on UK student loans and why your balance might grow even while you're repaying.
The basics: What is RPI?
Most UK student loan interest rates are based on RPI (Retail Price Index), a measure of inflation that tracks the cost of goods and services.
ℹ️How the rate is set
RPI changes each month. Student loan interest rates are typically updated in September each year using the March RPI figure. Check your Student Loans Company account or GOV.UK for the current rate applied to your plan.
Interest rates by plan type
💡Plan 2, Income-linked variable rate
While studying: RPI plus 3%
Earning under £28,470: RPI only
Earning £28,470–£52,195: RPI to RPI plus 3% on a sliding scale
Earning over £52,195: RPI plus 3%
Plan 2 is the only plan where higher earners pay a higher interest rate than lower earners.
ℹ️Plan 1 & Plan 4
Lower of:
- RPI, or
- Bank of England base rate plus 1%
This cap protects borrowers during high inflation periods
✅Plan 5
RPI only
No income-based element, the rate is the same regardless of what you earn
📝Postgraduate Loans
RPI plus 3%, a flat rate regardless of income
When does interest start accumulating?
Interest starts accumulating immediately from the day money is paid out:
- Tuition fee loans: Interest starts from the day it's paid to your university (usually start of each term)
- Maintenance loans: Interest starts from the day money enters your bank account
- While studying: Interest accumulates but no repayments are due
- After graduation: Interest continues while you repay
Example (illustrative, using a Plan 2 rate of 6.2%): A student starting in September 2022 with a £9,250 tuition loan would accumulate approximately £185 in interest by June 2025 at a 6.2% study-period rate. Check your SLC statement for the actual rate applied to your loan.
Why your balance might grow despite repaying
Loan balances can increase year after year even while making monthly payments. This happens when annual interest exceeds the annual repayment:
Worked example: Plan 2, £45,000 balance, £32,000 salary (using a 6.2% sample rate)
Annual repayment: (£32,000 - £28,470) × 9% = £318
Annual interest: £45,000 × 6.2% = £2,790
Net change: Balance grows by £2,472 this year
This is by design. The system expects most borrowers' balances to grow. Around 80% of Plan 2 borrowers will never fully repay their loans; they'll be written off after 30 years with a remaining balance.
Plan 2's income-linked interest explained
Plan 2’s sliding scale is the only one where the rate depends on income. This is how it works:
| Income Range | Interest Rate | Current Rate |
|---|---|---|
| Under £28,470 | RPI only | ≈3.2% |
| £28,470 | RPI + 0% | ≈3.2% |
| £35,000 | RPI + 0.83% | ≈4.0% |
| £40,000 | RPI + 1.46% | ≈4.7% |
| £52,195+ | RPI + 3% | ≈6.2% |
The interest rate increases gradually for each £1 earned between £28,470 and £52,195, reaching the maximum at £52,195.
⚠️Plan 2 income linked interest and statements
What salary do you need to start reducing your balance?
To actually reduce your loan balance, your annual repayments must exceed annual interest. This requires surprisingly high salaries:
Plan 2 (£45k balance)
Interest at 6.2%: £2,790 a year
Salary needed: ≈£59,500
At £59k, you pay £2,793 a year, just exceeding interest
Plan 4 (£25k balance)
Interest at 3.2%: £800 a year
Salary needed: ≈£41,600
Lower interest means balance reduces at more attainable salaries
Implication: Most Plan 2 graduates need to earn £60k+ before their balance starts decreasing. Below this, you're effectively paying a graduate tax with no realistic prospect of clearing the debt.
How often are rates updated?
Student loan interest rates are typically updated once per year:
- September 1st: New rates take effect
- Based on March RPI: Uses RPI figure from 5-6 months earlier
- Fixed for 12 months: Rate stays constant until next September
- No mid-year adjustments: Even if inflation changes dramatically
Example: The rate from September 2024 to August 2025 is based on March 2024's RPI of 3.2%, even if RPI rises to 5% during the year.
Should high interest rates make me overpay?
Even with interest rates as high as 6.2%, overpaying is rarely the right choice:
❌Why NOT to overpay (typical earner)
- You'll likely reach write-off with a remaining balance
- Overpayments are money you'll never see again
- Better to maximise pension contributions
- Can't get refunds if overpaid
✅When to consider overpaying
- Very high salary (£80k+) early in career
- Small remaining balance (<£15k)
- Confident you'll repay in full
- All other finances optimised
See our overpayment calculator and guide for personalized analysis.
Key takeaways
Interest starts from day one, even while you're still studying
Plan 2 penalizes high earners with up to 6.2% interest
Most borrowers' balances will grow despite making payments
You typically need £60k+ salary to reduce a Plan 2 balance
The system is designed for write-off, balance growth is expected
Student Loan Interest: Common Questions
- What is the interest rate on a UK student loan?
- It depends on your plan. Plan 1 and Plan 4 charge the lower of RPI or the Bank of England base rate plus 1%. Plan 2 charges between RPI and RPI plus 3% depending on your income. Plan 5 charges RPI only, with no income linked element.
- Why is my student loan balance going up?
- Your balance grows because interest is added faster than your repayments reduce it. On Plan 2, interest can reach RPI plus 3% which in some years has exceeded 7%. At typical graduate salaries, monthly repayments are much smaller than the interest being charged, so the balance rises.
- Does student loan interest matter?
- For most borrowers the interest rate makes no practical difference. Around 80% of Plan 2 borrowers will have their balance written off regardless of how much interest builds up. The interest rate only matters if you would actually repay the full amount, which requires sustained high earnings.
- When does student loan interest start?
- Interest starts from the day your first payment is made to your university or into your bank account. It accrues throughout your course, before you start repaying. By the time you graduate, interest has already been added to your balance for three or four years.