Why Did I Pay Student Loan Below the Threshold?
The causes of unexpected student loan deductions — and how to reclaim what you're owed
Key Takeaways
- Most common cause: a bonus or overtime payment pushed one month above the monthly threshold even though your annual salary is below the annual threshold. PAYE assesses each month independently.
- PAYE code errors apply the wrong threshold. Plan 1 is £2,172/month vs Plan 2 at £2,373/month — if you're on Plan 2 but coded as Plan 1, you start paying £201/month earlier than you should.
- Overlapping jobs: each employer assesses independently. Two £15k jobs — neither employer deducts, but your total £30k income exceeds the Plan 2 threshold. The reverse can also happen, causing over-deduction.
- Wrong plan assignment: if HMRC assigns Plan 1 instead of Plan 2, you cross the lower £2,172 monthly threshold sooner — deductions start at a lower income than your actual plan requires.
- You can reclaim overpaid deductions through HMRC, your employer's payroll, or a Self Assessment return. Refunds are paid in cash — not applied to your loan balance.
In this article
Common Causes
If you've spotted a student loan deduction on your payslip and your salary is below the repayment threshold, you haven't necessarily been charged incorrectly. Several legitimate reasons can produce this outcome — and one or two genuine errors also appear regularly.
The six most common causes are:
- A bonus or overtime payment pushed that month's gross pay above the monthly threshold
- Your PAYE code has the wrong loan plan type assigned
- You have two or more jobs and combined income triggers deductions differently across employers
- HMRC assigned the wrong plan, applying a lower threshold than your actual plan requires
- You have mixed employed and self-employed income with complex threshold interactions
- A genuine payroll processing error by your employer
Work through each section below to identify which applies to you. Most cases are resolved quickly once you know the cause.
Bonus and Overtime Months
This is the single most common explanation. PAYE student loan deductions use a Period 1 (non-cumulative) basis — your employer assesses each pay period independently, without reference to your annual earnings or previous months.
If your gross pay for any single month exceeds the monthly threshold, 9% is deducted on the excess. Your annual salary being below the annual threshold is irrelevant to what happens that month.
Worked Example — Plan 2, Christmas Bonus
Annual salary: £26,000 (£2,167/month)
Christmas bonus (December): £2,000
December gross pay: £2,167 + £2,000 = £4,167
Plan 2 monthly threshold: £2,448
Amount above threshold: £4,167 − £2,448 = £1,719
December deduction: 9% × £1,719 = £154.71
Every other month (£2,167) is below the £2,448 threshold, so no deductions apply. Your total annual income is £28,000, still below the £29,385 annual threshold, so the £154.71 is reclaimable.
The same applies to commission payments, shift allowances, back-pay, and any other lump sum added to your regular salary. Your employer cannot predict future months when processing your December payslip — they see £4,167 gross, compare it to £2,448, and deduct accordingly.
PAYE Code Errors
Your PAYE tax code includes a student loan indicator that tells your employer which plan type to use. If HMRC sends the wrong indicator, your employer applies the wrong monthly threshold — and you may be deducted from a lower income point than your plan requires.
Monthly Threshold Gap Between Plans
| Plan | Monthly Threshold | Annual Threshold |
|---|---|---|
| Plan 1 | £2,241 | £26,900 |
| Plan 2 | £2,448 | £29,385 |
| Plan 5 | £2,083 | £25,000 |
A Plan 2 graduate incorrectly coded as Plan 1 starts repaying at £2,172/month instead of £2,373/month. On a £28,000 salary, this means deductions every month when there should be none. The gap is £201/month — worth £22.59 in unnecessary deductions per month at 9%.
If you suspect a wrong plan type, check your payslip for the loan plan indicator (usually “SL” with a number) and compare it against your Student Finance correspondence. Contact HMRC to correct the code if it's wrong.
Overlapping Jobs
When you have two or more employers, each one calculates student loan deductions independently. They only see the income they pay you — they have no knowledge of your other jobs.
This creates two opposite problems:
Under-Deduction
Two jobs at £15,000 each (total £30,000). Neither employer deducts because each salary is below the Plan 2 monthly threshold of £2,448 (£1,250/month each).
But your combined income of £30,000 exceeds the £29,385 annual threshold. You owe repayments on £615, which is £55.35 per year, that were never deducted.
Over-Deduction
Two jobs at £30,000 each (total £60,000). Both employers deduct independently on income above the monthly threshold. Each employer calculates 9% on (£2,500 − £2,448) = £4.68/month.
Combined deductions: £9.36/month. But repayment should be calculated on total income above the threshold: 9% × (£60,000 − £29,385) = £2,755.35/year (£229.61/month). Here the combined deductions are far less than owed.
If you have multiple jobs, file a Self Assessment return each year. HMRC reconciles the total deductions against your combined income and resolves any under- or over-payment.
Wrong Loan Plan Assigned
HMRC determines your loan plan based on information from the Student Loans Company. Occasionally this information is inaccurate — especially if you have loans from different periods, studied in Scotland, or have a Postgraduate Loan alongside an undergraduate loan.
The most common mix-up is Plan 1 vs Plan 2. If you started university in England or Wales after September 2012, you should be on Plan 2 (monthly threshold £2,373). If HMRC assigns Plan 1 (monthly threshold £2,172), deductions start £201/month too early.
To check your plan type, log in to your Student Finance account or call the Student Loans Company. If there's a discrepancy, contact HMRC to correct your PAYE coding notice. Your employer implements whatever HMRC instructs — fixing the source data is the only solution.
Self-Employment Mix
If you have both employed and self-employed income, your employer deducts student loan through PAYE on your salary. HMRC then looks at your combined income through Self Assessment.
This can produce an apparent overpayment: your salary alone is below the annual threshold, so your employer should not deduct — but your combined salary plus self-employment profit does exceed the threshold. In this case, the PAYE deductions are correct and no refund is due.
Conversely, if your combined income is below the annual threshold, any PAYE deductions taken during the year (for example, in a bonus month) are overpayments. Declare everything on Self Assessment and HMRC will issue a refund for any excess.
How to Fix It
Step-by-Step Checklist
- Check your payslip. Look for the student loan line item and note the amount deducted. Check whether a plan type is shown (SL1, SL2, SL4, SL5, or PGL).
- Calculate your monthly gross pay. If your gross pay that month (including any bonus or overtime) was above the monthly threshold for your plan, the deduction is technically correct for that pay period.
- Verify your plan type. Log in to Student Finance England (or equivalent) to confirm your actual plan. Compare it to what your payslip shows.
- Contact HMRC if the plan is wrong. Call 0300 200 3300 and ask them to correct your PAYE coding notice. Provide your National Insurance number and Student Loans Company reference.
- Assess your annual total. Add up your total income for the tax year (from all sources). If it's below your plan's annual threshold, you're entitled to a refund of all deductions taken.
- Gather your P60 and payslips. You'll need these as evidence for any refund claim. Your P60 is issued after 5 April each year and shows total student loan deductions for the year.
If the issue is a genuine payroll error by your employer (for example, a technical glitch that doubled a deduction), contact your payroll or HR department first. They can correct this in the next pay run without needing to involve HMRC.
Claiming a Refund
If your total annual income was below the annual threshold but deductions were taken, you are entitled to a refund. You cannot claim until after the tax year ends on 5 April.
Timelines
- Tax year ends 5 April. Refunds can be claimed from this date.
- HMRC typically processes refunds within 6 weeks of receiving your claim or completed Self Assessment return.
- You have 4 years to reclaim an overpayment (e.g., overpayments from 2021/22 must be claimed before 5 April 2026).
Self Assessment Route
If you already file Self Assessment (for self-employment, rental income, or other reasons), declare your total income as normal. HMRC calculates the correct student loan liability and compares it to what was deducted. Any overpayment is refunded alongside your tax refund.
Direct Claim Route
If you do not file Self Assessment, contact HMRC directly:
- Phone: 0300 200 3300 (HMRC income tax helpline)
- Have your P60, payslips, and National Insurance number ready
- HMRC will verify the overpayment and arrange a refund by bank transfer or cheque
Important: Refunds Are Cash, Not Loan Reductions
Your refund is paid directly to you — it does not reduce your outstanding student loan balance. The deductions were never applied to your loan account in the first place (HMRC had not yet forwarded them to the Student Loans Company). You receive the cash; your loan balance remains unchanged.
For detailed guidance on the refund process and P60 documents, see our guides on P60 and student loan repayments and the repayment issues hub.
Related Guides
Monthly vs Annual Thresholds
Why each pay period is assessed independently and how this creates unexpected deductions.
Repayment Thresholds Guide
Current thresholds for all plan types and how they change each year.
Bonus Payments and Student Loans
How bonuses trigger deductions and what you can do about it.
Multiple Jobs and Student Loans
How deductions work across two or more employers and how to avoid under- or over-payment.
P60, P45 and Student Loan Repayments
How to use your end-of-year documents to check and reclaim overpaid deductions.
Student Loan Tax Code and Payslip
How to read your payslip and tax code to check whether the right plan is being applied.
Repayment Issues Hub
All guides on refunds, overpayments, employer errors, and fixing student loan deduction problems.
Student Loan Calculator UK Editorial Team
Editorial Team
This page is maintained by the Student Loan Calculator UK editorial team, checked against GOV.UK and Student Loans Company guidance. Read more about our editorial approach.