Clear Calculators
Short version: repayments are based on income above your plan threshold. Plan 1, Plan 2, Plan 4 and Plan 5 usually use 9% above the threshold. Postgraduate loans usually use 6% and can be collected at the same time as an undergraduate loan.
The basic student loan repayment formula
For a simple estimate, take the pay used for student loan purposes, subtract the threshold for the plan, then apply the repayment percentage to the amount left over. If pay is below the threshold for that period, the estimate is usually zero.
The period matters. Payroll often works weekly or monthly, while people tend to think about salary yearly. A bonus or overtime month can create a deduction even if your annual pay looks close to the threshold.
Plan 1, Plan 2, Plan 4, Plan 5 and postgraduate loans
Undergraduate plans
Plan 1, Plan 2, Plan 4 and Plan 5 have different thresholds. The usual payroll estimate is 9% of income above the selected plan threshold.
Postgraduate loans
Postgraduate loan repayments are usually estimated at 6% above the postgraduate threshold. They can apply at the same time as an undergraduate plan.
If you do not know your plan
Your plan depends on where you lived, when you started and the type of loan. Check Student Loans Company records or GOV.UK before treating an estimate as correct.
Is student loan taken before or after tax?
Student loan repayment is separate from Income Tax and National Insurance. Payroll usually works it out from repayment income, then deducts it from pay. It does not normally reduce taxable income like some pension arrangements can.
This is why pension method and salary sacrifice matter. Salary sacrifice can reduce contractual cash pay before some payroll calculations. Relief-at-source pension contributions are usually taken after tax. If both pensions and student loans apply, check the method rather than assuming every deduction works the same way.
Why your payslip can differ from a calculator
A payslip can differ because payroll uses weekly or monthly thresholds, rounding, employer start or stop notices, bonuses, overtime, refunds, multiple jobs and sometimes incomplete information. Self Assessment, overseas repayments and direct payments can also use different timing.
Use the calculator to check the shape of the deduction, then compare it with the payslip line and official records. For refund eligibility, plan status, overseas repayment or balance questions, check Student Loans Company or GOV.UK guidance.
Useful tools
Sources reviewed 6 July 2026: GOV.UK student loan repayment guidance and Clear Calculators bundled UK payroll assumptions. This guide is for checking and planning, not financial, tax, employment or legal advice.