Your student loan balance can keep rising even while money leaves your payslip every month. For many borrowers, that feels confusing. Repayments depend mainly on income, while the interest rate on student loans determines how quickly the outstanding balance grows.
That difference matters more in 2026 because new interest rates apply from September. Some borrowers could face interest of up to 6%, yet their monthly deductions may hardly change. Others may eventually repay the full balance, making the interest charged far more important.
So, how much interest are you really paying, and should you be worried about it? This guide explains the numbers, the September 2026 changes, and when student loan interest genuinely affects your finances.
Key Takeaways
- Student loan interest affects your balance rather than directly setting your monthly repayment.
- Most undergraduate plans collect 9% of earnings above the relevant repayment threshold.
- Plan 2 interest will range from 4.1% to a maximum of 6% from September 2026.
- Plan 5 interest will become 4.1% from September 2026.
How Student Loan Interest Works
Student loan interest begins when the first payment reaches you or your education provider. Interest continues until the loan is repaid or cancelled under the relevant rules. The Student Loans Company calculates interest daily and adds it to your balance each month.
The rate you pay depends mainly on your repayment plan. Plan 2 borrowers can also face different rates depending on their income and circumstances. This means two borrowers with similar balances could receive different interest charges.
Interest can continue even when you are not making compulsory repayments. Your repayment obligation depends on whether your income exceeds the relevant threshold. This is why a balance can rise while someone earns below that threshold.
(Source: Student Loans Company, Student loans: a guide to terms and conditions 2026 to 2027)
Student Loan Rates From September 2026
The Department for Education confirmed new rates on 10 August 2026. The applicable March RPI figure is 4.1% for the period from September 2026 to August 2027.
The main rates from 1 September 2026 are:
|
Repayment plan |
Interest from September 2026 |
|
Plan 1 |
Maximum 4.1%* |
|
Plan 2 |
4.1% to a maximum 6% |
|
Plan 5 |
4.1% |
|
Postgraduate Loan |
Maximum 6% |
*Plan 1 uses the RPI or bank base rate plus 1%, whichever is lower. The rate can therefore change during the academic year.
Plan 2 would normally allow interest up to RPI plus 3%. That would produce a maximum of 7.1% using the March 2026 RPI figure. However, the government has capped Plan 2 interest at 6% until 31 August 2027.
Postgraduate loans normally carry RPI plus 3% interest. Their calculated rate would also be 7.1% from September 2026. The same temporary 6% maximum will apply during this period.
Plan 5 works differently because its interest normally follows RPI only. The rate will therefore become 4.1% from September 2026.
(Source: Student Loans Interest Rates and Repayment Threshold Announcement)
What About Plan 4?
Plan 4 applies to borrowers with loans issued through Student Awards Agency Scotland. Repayments remain based on income rather than the amount borrowed.
Interest follows the previous March RPI or Bank Base Rate plus 1%, whichever is lower. The March 2026 RPI figure is 4.1%. Based on current rates, this points to 4.1%, although the rate can change if base rates fall.
Interest Is Not Your Repayment Rate
A 6% student loan interest rate does not mean you repay 6% of your salary. The interest percentage applies to your outstanding loan balance. Your compulsory repayment usually depends on earnings above the threshold for your plan.
For Plans 1, 2, 4 and 5, employees repay 9% of earnings above their applicable threshold. Postgraduate loan borrowers repay 6% above their separate threshold. These deduction rates remain unchanged for the 2026/27 tax year.
Student Loan Repayment Thresholds 2026/27
|
Plan |
Annual threshold |
Repayment rate |
|
Plan 1 |
£26,900 |
9% above threshold |
|
Plan 2 |
£29,385 |
9% above threshold |
|
Plan 4 |
£33,795 |
9% above threshold |
|
Plan 5 |
£25,000 |
9% above threshold |
|
Postgraduate Loan |
£21,000 |
6% above threshold |
These thresholds apply from 6 April 2026.
(Source: HMRC student loan deduction tables for 2026/27)
Your student loan deduction is only one part of your overall take-home pay. If you want to see how salary, income tax, national insurance, and other deductions affect your net income, use our salary calculator for a quick estimate.
This difference between interest and repayments is crucial. A higher interest rate can increase your balance without changing your next payroll deduction. Your deduction normally changes when your earnings or repayment threshold changes.
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Why Plan 2 Interest Varies
Plan 2 differs because post-study interest can depend on income. Borrowers on lower incomes normally pay RPI, while higher earners can face RPI plus up to 3%.
For 2026/27, the Plan 2 repayment threshold is £29,385. HMRC guidance places the upper income point at £52,885 for the normal maximum interest calculation. Between those figures, interest rises on a sliding scale.
From September 2026, the underlying range would normally start at 4.1% and reach 7.1%. The temporary cap means the maximum actually charged will be 6%.
This matters because higher earners can face larger deductions and a higher interest rate. Whether that increases their lifetime cost depends on how quickly they repay the balance.
(Source: Interest rate cap introduced to protect Plan 2 borrowers)
Does Higher Interest Increase Your Payslip Deduction?
Usually, it does not. Employers calculate student loan deductions using your earnings and the threshold for your plan. They do not calculate deductions from your outstanding student loan balance.
This means the September 2026 interest changes will not automatically increase your monthly deduction. A salary increase could increase it because more earnings would sit above your threshold.
Employers calculate deductions for each pay period. Therefore, monthly earnings can sometimes trigger a repayment even when annual income is relatively low.
What Happens When You Receive a Bonus?
Bonuses and overtime count towards income when student loan deductions are calculated. A large bonus can push one month’s earnings above the relevant monthly threshold. Your employer may therefore deduct more student loan repayment that month.
This can happen even when your annual income eventually falls below the annual threshold. In that situation, you may be able to request a refund after the tax year ends. Refunds are not automatic.
For example, someone may normally earn below their monthly threshold. A year-end bonus could produce a student loan deduction for that month. They should review their annual income after 5 April to check whether a refund is available.
Who Should Worry About the Interest Rate?
The headline interest rate matters differently depending on whether you are likely to repay the full balance. For some borrowers, part of the loan may eventually be cancelled under their plan’s rules. In those cases, a larger balance does not necessarily mean the same amount will leave their pocket.
Plan 2 loans are generally cancelled 30 years after the borrower first becomes due to repay. Plan 5 uses 40 years under current rules. Postgraduate Loans generally use 30 years.
Interest can matter more for borrowers expected to clear the loan before cancellation. A higher rate can increase the amount they need to repay before reaching a zero balance.
This is why comparing student loans with ordinary personal debt can be misleading. An ordinary loan usually requires repayment of the full outstanding balance. Income-contingent student loans work under different repayment and cancellation rules.
Should You Make Extra Repayments?
You can make voluntary student loan repayments without an early repayment penalty. However, making extra payments is not automatically the best financial decision.
Additional repayments can be more attractive when you are highly likely to repay the balance in full. Reducing the balance could then reduce future interest. The potential benefit depends on your expected income, remaining balance, and repayment period.
The calculation looks different when a significant balance may eventually be cancelled. Paying thousands voluntarily could simply reduce an amount that you would never have repaid anyway.
Before making a large payment, also consider your wider finances. High-interest debts and emergency savings may deserve priority. Personal circumstances should drive the decision rather than the headline student loan rate alone.
Can You Repay More and Reduce PAYE Deductions?
Normally, no. Making a voluntary repayment does not reduce the amount your employer must deduct from future salary. The normal income-based repayment rules continue to apply.
This is an important point before making a substantial voluntary payment. Paying £5,000 directly towards your balance does not normally stop the next payroll deduction.
Only clearing the loan entirely would eventually end deductions. Borrowers approaching full repayment should monitor their balance carefully to avoid overpaying.
Student Loans Through Payroll
Employees normally repay student loans through PAYE. Employers deduct the appropriate amount alongside income tax and national insurance when earnings exceed the relevant threshold.
Your payslip should show student loan deductions separately. Employers receive instructions about the appropriate repayment plan, but they do not receive your outstanding loan balance.
Incorrect plan information can result in the wrong deductions. Accurate payroll processing is therefore important for employers managing student loan deductions.
Student Loans and Self Assessment
Self-employed borrowers usually make student loan repayments through Self Assessment. The repayment forms part of the amount calculated using income reported on the tax return.
The same income-based principle applies. Your student loan balance does not directly determine the Self Assessment repayment. The calculation uses taxable income and the threshold for your plan.
This can create a larger January payment than some taxpayers expect. Good cash flow planning can help avoid surprises when tax and student loan repayments become due together.
How to Check Your Real Student Loan Cost
Looking only at your outstanding balance can give an incomplete picture. You should consider your interest rate, compulsory repayments, expected earnings, and remaining cancellation period together.
Start by confirming which repayment plan applies to you. Then check the interest added to your online student loan account and compare it with your annual repayments.
If repayments consistently exceed annual interest, your balance may begin falling more quickly. If interest remains higher, the balance can continue increasing despite regular payroll deductions.
The most useful question is therefore not simply, “What interest rate am I paying?” A better question is whether that interest will change the amount you ultimately repay.
Conclusion
The interest rate on student loans is important, but it does not tell you what your next repayment will be. Income, repayment thresholds, loan type, and the remaining repayment period all affect the real cost.
From September 2026, Plan 2 and postgraduate interest will be capped at 6%, while Plan 5 moves to 4.1%. Understanding these changes can help you decide whether a growing balance should actually influence your financial decisions.
If student loan repayments are affecting your tax position or Self Assessment bill, professional tax planning advice can help you understand the wider impact.
