Do I pay back undergraduate and postgraduate student loans at the same time?

Yes. The Postgraduate loan is calculated against its own £21,000 threshold at 6%, on top of whichever undergraduate Plan you hold (Plan 1, 2, 4 or 5 at 9% over their threshold). Both come out of your payslip in parallel.

When is a UK student loan written off?

Plan 1: 25 years from when the loan becomes repayable. Plan 2, Plan 4 and Postgraduate: 30 years. Plan 5 (new English borrowers from September 2023): 40 years. Most Plan 5 borrowers do not clear the balance before the 40-year write-off.

How much interest does the UK student loan charge?

It depends on the plan. Plan 1, Plan 4 and Plan 5 charge RPI only — currently about 4.3% per year. Plan 2 slides between RPI (low earners) and RPI + 3% (earners over £51,245). Postgraduate loans charge RPI + 3%, currently about 7.3%.

UK student loan repayment calculator

Pick the plans you have, drop in a starting salary, see what you actually repay each year and whether you ever clear the balance. Combine Plan 1 / 2 / 4 / 5 with a Postgraduate loan — both come out of your payslip in parallel.

Your scenario

Starting annual salary

Salary growth / year

Starting age

Plans you hold

Tick all that apply. Most people have exactly one undergraduate plan; postgraduates often have an undergraduate plan plus the postgraduate loan in parallel.

Plan 1 — threshold £26,065, 9%, 25-year term Started an English or Welsh undergraduate course before September 2012, or started a Northern Irish course at any point.

Plan 2 — threshold £28,470, 9%, 30-year term Started an English or Welsh undergraduate course between September 2012 and August 2023.

Plan 4 — threshold £32,745, 9%, 30-year term Started a Scottish undergraduate course at any point — moved off Plan 1 onto Plan 4 from 2021.

Plan 5 — threshold £25,000, 9%, 40-year term Started an English undergraduate course from September 2023 onwards. Forty-year term — most graduates will not clear the balance.

Balance £

Postgrad — threshold £21,000, 6%, 30-year term A postgraduate masters or doctoral loan. Repaid simultaneously with any undergraduate plan you already hold.

Year one

Annual repayment: £630
Per month: £53
Interest this year: £2,365

Your annual repayment is less than the interest accruing — your balance is growing, not shrinking. This is normal early in a career; what matters is whether your salary ever overtakes the interest line, or you ride out the write-off term.

Lifetime

Total repaid: £127,156
Total interest accrued: £127,196
Written off: £55,041

Plan 5 Written off (year 40), £55,041 unpaid

Methodology and sources

Plan thresholds, rates and term lengths are taken from gov.uk – Repaying your student loan and valid for the 2025-26 academic year. They are updated annually on 6 April; when DfE publishes new figures we update them in a single place.
Interest is modelled at an indicative 4.3% (RPI baseline) for Plan 1, Plan 4 and Plan 5; 7.3% for Postgraduate (RPI + 3%); and the official sliding scale (RPI to RPI + 3%) for Plan 2. Actual rates re-set each September and depend on the prior March's RPI figure.
Repayment is calculated per plan independently: combined Plan X + Postgraduate users repay both in parallel out of their payslip.
This is an illustrative calculator, not financial advice. The Student Loans Company is the authoritative source for your actual balance.