Overpaying feels responsible — but a UK student loan isn’t a normal debt. If yours would be written off before you’d clear it, every extra pound you pay is a gift to the Treasury. Check the maths for your plan before you send the SLC a penny more. Free, instant, and nothing is recorded.
Rates to Aug 2026: Plans 1, 4 & 5 charge 3.2%; Plan 2 charges 3.2–6.2% depending on income; Postgrad 6.2%. From Sept 2026 these become 4.1% and a 6% cap — the slider resets to your plan’s top rate when you switch plan.
Use an after-tax rate — a cash ISA or top easy-access account pays 4–5% today. Long-run index investing has averaged more, but it isn’t guaranteed.
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Assumes 2026/27 repayment thresholds (Plan 1 £26,900, Plan 2 £29,385, Plan 4 £33,795, Plan 5 £25,000, Postgrad £21,000) rising 2.5% a year, your chosen interest and savings rates staying fixed, monthly compounding, and your salary growing once a year. Repayments are 9% of pay above the threshold (6% for Postgrad). Loans are written off 25 years (Plan 1), 30 years (Plans 2, 4 and Postgrad) or 40 years (Plan 5) after the April you were first due to repay; Plans 1 and 4 also write off at age 65, which this tool ignores. ‘Save it’ assumes every pound you don’t send the SLC goes into savings instead — including your old repayments once a loan is cleared. This is an illustration, not financial advice; nothing you enter is stored or sent anywhere.
A UK student loan behaves nothing like a credit card or a mortgage. Your monthly payment is set by your income, not your balance — 9% of everything you earn above your plan’s threshold (6% for postgraduate loans) — and after 25 to 40 years, whatever is left is written off completely. That flips the usual logic of debt on its head: the balance and the scary interest rate often just don’t matter, because they only change how fast a number grows that you were never going to finish paying anyway. In practice it works far more like a graduate tax than a loan.
The honest rule of thumb: if the calculator shows your loan being written off, put the money in savings instead — see what it compounds into with the savings calculator. If it shows you clearing the loan either way, compare the loan rate with the best savings rate you can get and let the bigger number win. And if you’re not sure what you’re actually paying each month, the salary calculator breaks your payslip down line by line, student loan included.
It depends on your plan, counted from the April you were first due to repay (the April after you finished your course): Plan 1 after 25 years, Plan 2 after 30 years, Plan 4 (Scotland) after 30 years, Plan 5 after 40 years, and Postgraduate Loans after 30 years. Plans 1 and 4 are also written off when you turn 65 if that comes sooner. Whatever is left on that date is cancelled — you don’t owe it, and it never appears on your credit file.
Probably not. Your monthly repayment is fixed by your salary (9% of pay above the threshold, or 6% for postgrad), so a growing balance doesn’t cost you a penny more per month. The balance only matters if you’re on track to clear it before write-off. For everyone else it’s an alarming-looking number that will one day be deleted — which is why the interest rate scaremongering around student loans is mostly noise.
People who will clearly repay in full: typically higher earners with smaller balances — say a £15,000 balance on a £60,000 salary — especially on Plan 2 or postgraduate interest rates that beat savings accounts. If the calculator shows you clearing the loan years before write-off in both columns, overpaying is a genuine, guaranteed, tax-free return. If either column says ‘written off’, keep your money.
It never appears on your credit file, so it doesn’t touch your credit score. Mortgage lenders do count the monthly repayment in affordability calculations — it reduces how much you can borrow slightly, the same way any salary deduction does — but clearing your student loan early to help a mortgage application rarely stacks up against simply having the cash for a bigger deposit.
You still owe repayments while abroad (the SLC sets fixed country thresholds), and self-employed repayments are collected through Self Assessment. Career breaks, part-time years and redundancy all mean months of zero repayments — which pushes you further towards write-off and makes past overpayments more likely to have been wasted. If your future income is uncertain, that’s an argument for saving, not overpaying: savings stay yours either way.
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£100 a month you don’t send to the SLC can be tens of thousands of pounds by write-off day — in your name, not the Treasury’s.
