Your Student Loan Is Charging 6.2% Interest — Every Month You Don't Overpay Costs You Real Money

Student loan interest isn't a flat number — the full repayment plans explained here. Plan 2 borrowers face a sliding scale tied to RPI inflation plus a margin:

• Earning £29,385 or less: 3.2% interest (RPI only)
• Earning between £29,386 and £52,885: 3.2% plus up to 3% extra, graduated by income
• Earning £52,885 or more: the full 6.2% (RPI + 3%)

That 6.2% rate compounds daily on the outstanding balance. On a typical £50,000 balance, that's £3,100 a year in interest alone — £258 every month where your balance grows instead of shrinks. Over a decade of inaction, a £50,000 balance at 6.2% grows to over £91,000 before mandatory PAYE repayments are considered.

Plan 1 and Plan 5 borrowers at 3.2% have a weaker case for overpaying — you can beat that rate in a cash ISA paying 4.55% or a top easy-access savings account. But Plan 2 and Postgraduate borrowers at 6.2%? That's a different calculation entirely. The Student Loans Company doesn't advertise this clearly, but at 6.2% your student loan is the most expensive debt many graduates carry — more expensive than most mortgages and car finance deals.

The write-off question is binary: will you repay in full before the 30-year clock expires, or won't you? Get this wrong in either direction and it costs you real money.

If you graduated in 2015 with £50,000 of debt and earn £45,000 today, your mandatory repayments are £1,405 a year (9% of income above the £29,385 threshold). At 6.2% interest on the balance, you're barely covering the interest charge. The debt is growing, not shrinking. Write-off in 2045 is your exit — and overpaying would be foolish.

But change the salary to £60,000. Now you're repaying £2,755 a year through PAYE while being charged roughly £3,100 in interest on a £50,000 balance. You're still slightly underwater — but salary growth, promotions, and career progression tip the balance fast. If your income reaches £75,000-£80,000 within five years, you're almost certainly repaying in full. The ONS earnings data shows that graduates in professional occupations typically reach these levels by their mid-30s.

For that cohort — graduates earning above median who expect continued growth — every £1,000 overpaid today saves approximately £62 in interest next year. And that saving compounds. Over 15 years, a £5,000 lump sum overpayment today saves approximately £6,800 in total interest. That's a 136% cumulative return, guaranteed, with zero market risk and zero volatility.

Compare that to a stocks and shares ISA returning a historical average of 7-8% nominal. After accounting for volatility, the emotional cost of watching your portfolio crash during geopolitical crises like the current Iran situation, and sequence-of-returns risk for shorter timeframes, the student loan overpayment wins on risk-adjusted terms for any horizon under 15 years.

Student loan overpayments deliver a tax-free return. There's no income tax, no capital gains tax, no dividend tax on the interest you avoid paying. The HMRC guidance on tax-free savings confirms the personal savings allowance for higher-rate taxpayers is just £500 — everything above that is taxed at 40%.

A higher-rate taxpayer earning 5% in a savings account keeps 3% after tax (once the £500 personal savings allowance is exhausted). A Plan 2 borrower overpaying their loan effectively earns 6.2% — tax-free. To match that in a taxable savings account, you'd need a gross rate of 10.3%. No savings account in the UK pays 10.3%. No fixed-rate bond comes close.

The only comparable guaranteed return is overpaying your mortgage — and even mortgage rates for most borrowers are below 6.2% right now, with typical two-year fixes around 4.5-5%.

For basic-rate taxpayers the gap is narrower but still significant. A 20% taxpayer keeping 3.74% after tax from a 4.68% savings account still falls short of the 6.2% guaranteed, tax-free return from overpaying.

Don't drain your emergency fund. Don't skip your employer pension match. But after those non-negotiables, Plan 2 borrowers on track to repay in full should consider directing surplus cash to student loan overpayments before ISA contributions.

The Student Loans Company accepts voluntary payments through your online account, by bank transfer, or by cheque. There's no penalty for overpaying, and no minimum amount. Payments are applied directly to the principal, reducing the balance on which future interest is calculated.

A practical approach for a £55,000 earner with a £45,000 Plan 2 balance:

1. Emergency fund: 3-6 months' expenses in easy-access savings
2. Pension: contribute enough to capture the full employer match — this is free money
3. Student loan: direct £200-£400/month in voluntary overpayments
4. ISA: use the remaining £20,000 allowance for long-term wealth building

The order matters. The pension match is a 100% immediate return. The student loan overpayment is a guaranteed 6.2% return. The ISA is an expected but uncertain return averaging 7-8% historically. Stack your certainties first, then take calculated risks with what remains.

For graduates who also carry a mortgage, compare the rates directly. If your mortgage is at 4.5% and your student loan charges 6.2%, the student loan overpayment offers a better risk-free return. Our mortgage guide covers the overpayment comparison in more detail.

Not everyone on Plan 2 should overpay. If you're earning £35,000 with a £45,000 balance and limited salary growth prospects, the maths probably favours letting the loan run to write-off — see the case against overpaying. Your mandatory repayments won't cover the interest, and voluntary payments would be throwing money at a debt that disappears in 2045 regardless.

Plan 1 borrowers at 3.2% can beat that rate in a cash ISA or high-interest savings account. Plan 5 borrowers (post-2023 starters) also pay just 3.2%, and their loans aren't written off for 40 years — a longer runway that changes the calculation.

The sweet spot for overpaying is Plan 2 borrowers earning £50,000+ who expect their income to keep rising. If that's you, the 6.2% guaranteed return is the best risk-free deal in UK personal finance right now.

This article is for informational purposes only and does not constitute financial advice. You should seek independent financial advice before making any investment decisions.