Student Loan Payoff vs Invest Calculator
Compare aggressive voluntary loan repayments against investing in a tax-free Stocks & Shares ISA. Model official 30-year and 40-year statutory write-off policies under UK law.
Student Loan Parameters
Applicable to English and Welsh undergraduate courses started between 1 Sept 2012 and 31 July 2023.
Overpayment vs Investment Choice
Cash you could either pay off your loan with OR invest into a Stocks & Shares ISA.
Historical long-term nominal return of a global equity index tracker is 7%–8%.
Invest in an ISA: You Build Far Greater Wealth
By investing £150/mo into a tax-free ISA compounding at 7%, you accumulate £121,817.65, leaving you £79,769.98 richer than if you had poured that cash into the loan.
Statutory 2026/27 Student Loan Rules to Keep in Mind
- Not a Commercial Loan: UK student loans do not appear on credit files and do not affect mortgage credit scoring, though monthly deductions are factored into affordability stress tests.
- The 9% Flat Surtax: You only repay 9% of earnings above the £29,385 threshold. If you lose your job or earnings drop below the threshold, deductions immediately drop to £0.
- Automatic Cancellation: Under Section 22 of the Teaching and Higher Education Act 1998, any remaining debt is completely cancelled after 30 years. There is zero tax penalty on the written-off balance.
| Year | Gross Salary | Loan Rate | Balance (Min) | Balance (Overpay) | ISA Value |
|---|---|---|---|---|---|
| Yr 1 | £38,000 | 5.3% | £46,627 | £44,827 | £1,926 |
| Yr 2 | £39,140 | 5.5% | £48,314 | £44,615 | £3,987 |
| Yr 3 | £40,314 | 5.7% | £50,069 | £44,361 | £6,192 |
| Yr 4 | £41,524 | 5.8% | £51,903 | £44,060 | £8,551 |
| Yr 5 | £42,769 | 6.0% | £53,824 | £43,709 | £11,076 |
| Yr 6 | £44,052 | 6.2% | £55,845 | £43,302 | £13,777 |
| Yr 7 | £45,374 | 6.4% | £57,978 | £42,833 | £16,668 |
| Yr 8 | £46,735 | 6.6% | £60,238 | £42,295 | £19,760 |
| Yr 9 | £48,137 | 6.8% | £62,643 | £41,681 | £23,070 |
| Yr 10 | £49,581 | 7.0% | £65,211 | £40,981 | £26,610 |
The UK Student Loan: Why It Behaves as a Graduate Tax
In the United Kingdom, student loan debt is fundamentally different from a commercial mortgage, personal loan, or credit card balance. Administered under the Teaching and Higher Education Act 1998 and subsequent Education (Student Support) Regulations, repayments are linked strictly to your gross earnings rather than the size of the loan balance.
Graduates repay a flat 9% of earnings above the statutory threshold(or 6% for Postgraduate Master's loans) through HMRC's PAYE payroll system. Crucially, if you do not earn enough over your working lifetime to clear the debt, the remaining principal and accrued interest are completely cancelled after 30 years (Plan 2) or 40 years (Plan 5) with zero tax penalty.
Official 2026/27 Student Loan Plan Thresholds & Terms
| Plan | 2026/27 Threshold | Deduction Rate | Interest Rate Formula | Cancellation Term |
|---|---|---|---|---|
| Plan 1 | £26,900 / yr | 9% | Lower of RPI or Base + 1% | 25 years (or age 65) |
| Plan 2 | £29,385 / yr | 9% | RPI to RPI + 3% (Tiered) | 30 years |
| Plan 4 (Scotland) | £33,795 / yr | 9% | Lower of RPI or Base + 1% | 30 years (or age 65) |
| Plan 5 (2023+ Eng) | £25,000 / yr | 9% | RPI Only (No Surcharge) | 40 years |
| Postgraduate | £21,000 / yr | 6% | RPI + 3% | 30 years |
The Overpayment Trap: Why Most Plan 2 Graduates Lose Money
According to official forecasts from the UK Department for Education (DfE), only around 20% to 25% of undergraduates on Plan 2 will repay their student loan balance in full before the 30-year write-off date. For the remaining 75% to 80%, any voluntary lump sums or monthly overpayments are effectively wasted:
- Zero Payslip Relief:Making an extra £200 monthly repayment does not lower your next month's statutory PAYE deduction by a single penny. Your 9% payroll deduction remains identical.
- Subsidising the Government: When you voluntarily repay £10,000 against a £45,000 loan that was destined to be forgiven after 30 years, you have not saved £10,000 of your own money—you have simply saved HM Treasury £10,000 of statutory debt forgiveness.
- Opportunity Cost:If that same £200/month had been deposited into a Stocks & Shares ISA averaging 7% annual compounding growth, you would possess approximately £244,000 in liquid, tax-free wealth after 30 years.
Smart Move: Pension Salary Sacrifice Beats Overpaying
If your employer operates an approved salary sacrifice pension scheme, contributing additional income directly into your workplace pension reduces your gross contractual salary. Under statutory rules, this reduces your Income Tax, Class 1 National Insurance, AND your 9% Student Loan deduction simultaneously! For a higher rate taxpayer with a Plan 2 loan, this recovers up to 51% instant statutory relief on every pound contributed.
Frequently Asked Questions
Clear answers based on official HMRC rules and statutory guidance.
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Repayments are not the same as interest
Check the plan in your student finance account before comparing repayments. Pay-period thresholds and rounding can differ from annual threshold divided by twelve.
An undergraduate plan and a Postgraduate Loan may run together. A widget with one plan selector models one at a time; any combined comparison table is an annual illustration. Interest, cancellation dates and future earnings need separate assumptions.
Check the rules for your circumstances
Official guidance supports the rules described here; it does not approve or certify this calculator. Confirm dates, eligibility and unsupported cases before making a financial decision.