Student Loan and Tax Codes Explained

Tax Codes and Student Loans Are Separate Systems

One of the most common misconceptions among UK graduates is that their student loan repayment is somehow embedded in their tax code. It is not. Your tax code — the familiar combination of numbers and letters like 1257L — tells your employer how much income tax to deduct from your pay. It reflects your Personal Allowance, any adjustments for benefits in kind, and other tax-related factors. Student loan repayments are handled through an entirely separate mechanism.

When HMRC determines that you have a student loan and your earnings are likely to exceed the repayment threshold, they send a document called a "start notice" to your employer. This notice is separate from the tax code notification and instructs your employer to begin deducting student loan repayments using the rules for a specific plan type. The plan types are identified by codes: SL1 for Plan 1, SL2 for Plan 2, SL4 for Plan 4, and PGL for Postgraduate Loans. These codes appear on your payslip alongside your deductions.

The practical implication is that if your tax code is wrong, it does not affect your student loan deductions, and if your student loan plan code is wrong, it does not affect your income tax. They need to be corrected through different channels. Understanding this distinction saves you time when resolving issues, because you will know exactly whom to contact and what to ask for.

How HMRC Notifies Your Employer

HMRC is the bridge between the Student Loans Company (which administers your loan) and your employer (who deducts the repayments from your pay). Here is how the process works from start to finish.

When you take out a student loan, the Student Loans Company creates a record of your debt. Once you finish or leave your course, the SLC informs HMRC that you have a student loan and which plan type it falls under. HMRC then monitors your employment records through the PAYE (Pay As You Earn) system. When you start a new job and your employer registers you with HMRC, or when your pay exceeds the repayment threshold, HMRC sends a start notice to your employer through the electronic PAYE system.

The start notice contains two key pieces of information: the fact that you have a student loan, and which plan type applies. It does not tell your employer how much you owe, what your balance is, or when your loan will be written off — those details are between you and the SLC. Your employer only needs to know the plan type so they can apply the correct threshold and percentage to calculate your deduction each pay period.

In some cases, HMRC may not send the start notice immediately. This can happen if there is a delay in the SLC updating their records, if you have recently changed jobs and the new employer's PAYE registration has not yet been processed, or if HMRC's systems have not linked your student loan record to your new employment. If your employer does not receive a start notice, they will not make any student loan deductions — and they are not required to. The obligation lies with HMRC to issue the notice.

When you start a new job, your employer may also give you a Starter Checklist (which replaced the old P46 form). This checklist asks whether you have a student loan and, if so, which plan type. Your answer helps your employer apply the correct deductions while waiting for the official start notice from HMRC. However, the Starter Checklist is a temporary measure — the formal start notice from HMRC takes precedence once it arrives.

Understanding Your Tax Code

While your tax code does not include student loan information, it is still important to understand what it means so you can distinguish between tax and student loan issues on your payslip.

The standard tax code for the 2026/27 tax year is 1257L. The number represents your tax-free Personal Allowance (£12,570 divided by 10), and the letter "L" indicates that you are entitled to the standard allowance. Other common letters include "BR" (all income taxed at the basic rate, often used for a second job), "0T" (no Personal Allowance, sometimes used when HMRC does not have enough information), and "K" (used when deductions exceed your allowance, for example due to taxable benefits).

If your tax code changes, it affects how much income tax you pay but has no bearing on your student loan deduction. Similarly, if you receive a P2 Tax Code Notice from HMRC showing your updated tax code, it will not mention your student loan unless HMRC includes a note about the start notice being issued separately.

Occasionally, graduates see an unexpected change in their take-home pay and assume their student loan deduction has changed when, in fact, it is a tax code adjustment. Always check both elements separately on your payslip before raising a query.

What to Do If the Wrong Plan Is Applied

Being on the wrong student loan plan means your employer is using the wrong threshold to calculate your deduction. Since each plan has a different threshold — £26,900 for Plan 1, £29,385 for Plan 2, £33,795 for Plan 4 — the wrong plan can result in you paying too much or too little each month.

For example, if you are on Plan 4 (threshold £33,795) but your employer has been told to apply Plan 1 (threshold £26,900), your monthly deduction will be higher than it should be because the Plan 1 threshold is lower. On a salary of £36,000, you would pay 9% of (£36,000 minus £26,900) per year under Plan 1, which is about £819, compared with 9% of (£36,000 minus £33,795) under Plan 4, which is about £198 — a difference of over £621 per year.

If you discover that the wrong plan is being applied, follow these steps. First, confirm which plan you are actually on by checking your Student Loans Company online account or looking at your original loan paperwork. Second, contact HMRC — not your employer — and explain that the wrong plan code has been applied. HMRC will investigate and, if they agree, issue a corrected start notice to your employer. Third, ask HMRC whether you are entitled to a refund for any overpayments. Overpayments caused by the wrong plan code should be refunded, although it can take several weeks for the money to come through.

Your employer cannot change your plan code on their own initiative. They must follow the instructions on the start notice from HMRC. Even if you show your employer proof that you are on a different plan, they are legally obliged to use the plan code on the notice until HMRC issues an updated one. This protects both you and your employer from errors.

Start Notices and Stop Notices

HMRC issues two types of notices related to student loans: start notices and stop notices. Understanding both is key to ensuring your payslip is accurate throughout the life of your loan.

A start notice (form SL1) tells your employer to begin deducting student loan repayments. It specifies the plan type and is issued when HMRC's records show that you have a student loan and are employed. If you change jobs, HMRC issues a new start notice to your new employer. There may be a gap of a few weeks between starting a new job and the new employer receiving the start notice, during which no deductions are made. These missed deductions are not usually chased — the system adjusts over time.

A stop notice (form SL2) tells your employer to stop deducting student loan repayments. This is issued when the Student Loans Company confirms that your loan has been fully repaid or when the loan reaches its write-off date. The SLC informs HMRC, and HMRC sends the stop notice to your employer. There can be a delay of several weeks between your loan being cleared and the stop notice reaching your employer, which is why some graduates see deductions continue for a month or two after their balance reaches zero. Any over-deductions are refunded by the SLC.

If you are approaching the end of your loan and want to avoid over-deductions, the SLC recommends switching to direct debit for your final repayments. This way, you can control the exact amount you pay and stop payments as soon as your balance reaches zero, rather than relying on the payroll system to catch up. You can arrange this through your SLC online account.

Checking Your Tax Code and Student Loan Status Online

HMRC provides several ways to check your tax code and student loan status without needing to make a phone call. The most convenient is the HMRC Personal Tax Account, which you can access at gov.uk using your Government Gateway login.

Once logged in, navigate to the "Pay As You Earn (PAYE)" section. Here you will see your current tax code for each employment, along with details of how it was calculated. You will also see any student loan notices that have been sent to your employer. The display will show the plan type (Plan 1, Plan 2, Plan 4, or Postgraduate Loan) and the date the notice was issued.

If the information is incorrect — for example, it shows Plan 1 when you should be on Plan 2, or it does not show any student loan when you know you have one — you can report the issue directly through the Personal Tax Account. HMRC will investigate and update their records.

You can also use the HMRC app, available for iOS and Android, which provides similar information in a mobile-friendly format. The app shows your tax code, employment details, and any student loan notices, and allows you to report changes or errors.

For your student loan balance and detailed repayment history, you need to log into the Student Loans Company's separate online service at repayment.slc.co.uk. The SLC and HMRC are different organisations, and while they share data, they have separate online portals. The SLC portal shows your outstanding balance, repayment history, interest charged, and projected repayment or write-off dates.

Common Issues and How to Resolve Them

Over the years, a number of recurring issues have affected graduates' student loan deductions. Here are the most common ones and the steps to resolve them.

Deductions Starting at a New Job

When you start a new job, there can be a delay before your new employer begins deducting student loan repayments. This is normal and is caused by the time it takes for HMRC to process your new employment and issue a start notice. In the meantime, your employer may ask you to complete a Starter Checklist, where you declare your student loan status. Based on your declaration, they may begin deductions before the formal notice arrives. If they do not, and a few months pass without deductions appearing, contact HMRC to check whether the start notice has been issued.

Two Student Loans Running at the Same Time

If you have both an undergraduate loan (Plan 1, 2, 4, or 5) and a Postgraduate Loan, you will have two separate deductions on your payslip. Each has its own threshold and percentage. They run concurrently, meaning both are deducted simultaneously when your income exceeds both thresholds. This is not an error — it is how the system is designed. The combined deduction can be significant: for example, 9% above the undergraduate threshold plus 6% above the PGL threshold on a £40,000 salary could total over £2,000 per year.

Student Loan Deductions After Leaving the UK

If you move abroad, you are no longer in the PAYE system and your UK employer (if you still have one) stops deducting. However, you are still obligated to repay your student loan. The SLC will contact you to set up alternative repayment arrangements based on your overseas income. Your repayment threshold may differ depending on your country of residence. Failing to set up overseas repayments can result in penalties. Contact the Student Loans Company before you move to arrange this.

Self-Employment and Student Loans

If you are self-employed, student loan repayments are calculated as part of your Self Assessment tax return rather than through PAYE. You report your income to HMRC and they calculate the student loan repayment due alongside your income tax and National Insurance. The threshold and percentage are the same as for employed earners, but the payment is made annually (or in two instalments) rather than monthly. This means self-employed graduates pay their student loan in larger, less frequent chunks. Use our student loan calculator to estimate your annual repayment based on your self-employment income.

Tax Code Changes That Coincide with Student Loan Issues

Sometimes a graduate notices a change in take-home pay and cannot identify the cause. It may be a combination of a tax code change and a student loan adjustment happening in the same month. For example, you might receive a new tax code because of a company benefit, and simultaneously your employer receives a start notice for your student loan. The combined effect on your pay can be confusing. Always examine each deduction line separately on your payslip to isolate the cause of any change.

Key Takeaways

• Your tax code and student loan deduction are managed through separate HMRC systems.
• HMRC sends a start notice (SL1 form) to your employer specifying your plan type.
• Your employer cannot change your plan code without an updated notice from HMRC.
• Check your student loan status via the HMRC Personal Tax Account at gov.uk.
• Wrong plan codes should be reported to HMRC, not your employer.
• A stop notice is issued when your loan is repaid or written off.
• Self-employed borrowers repay through Self Assessment, not PAYE.
• If you have both an undergraduate and postgraduate loan, two deductions appear on your payslip.