Claim Your £1,847 Tax Rebate as an Office Worker
Last updated: March 2026 · Worked example — not professional advice.
This worked example shows how a typical office worker can end up overpaying tax due to an incorrect tax code — and how to calculate and claim back the difference. The numbers are based on 2025/26 HMRC rates and are illustrative, not based on a real individual.
Profile Summary
- Name: Rachel Hargreaves (fictional)
- Role: Marketing coordinator at a mid-size company in Manchester
- Gross salary: £32,000 per year
- Tax region: England
- Tax year: 2025/26
- Problem: Employer applied tax code BR instead of 1257L after Rachel changed jobs in September
What Went Wrong
When Rachel started her new job, her previous employer hadn't sent her P45 in time. The new employer, lacking the P45, applied the emergency tax code BR — which taxes all income at 20% with no personal allowance. Rachel didn't check her first payslip carefully and didn't notice the issue for five months.
Under the BR code, all £32,000 of her salary was taxed at 20%, resulting in £6,400 of tax for the year. Under the correct code of 1257L (giving her the full £12,570 personal allowance), her tax should have been calculated on only £19,430 of taxable income.
Step-by-Step Calculator Walkthrough
- Go to the tax rebate calculator
- Select "Wrong Tax Code" as the rebate type
- Set tax year to 2025/26 and region to England
- Enter gross income: £32,000
- Enter actual tax code used: BR
- Enter correct tax code: 1257L
- Click Calculate Rebate
Results
| Item | Amount |
|---|---|
| Gross Income | £32,000.00 |
| Tax under BR code (all at 20%) | £6,400.00 |
| Personal Allowance (1257L) | £12,570.00 |
| Taxable income (correct) | £19,430.00 |
| Tax due (correct, at 20%) | £3,886.00 |
| Estimated Refund | £2,514.00 |
Key Takeaways
- Always check your first payslip at a new job. Look for the tax code — it should match what's on your P45 or the standard 1257L.
- Emergency tax codes are temporary — they should be corrected once your P45 arrives. If they're not corrected within a month, contact your payroll department or HMRC.
- You can claim the overpayment back through your Personal Tax Account online, by calling HMRC, or by waiting for a P800 letter. The online route is fastest.
- The refund can be substantial — in Rachel's case, over £2,500. The longer the wrong code is applied, the larger the overpayment.
Frequently Asked Questions
How quickly can I fix a wrong tax code?
Call HMRC on 0300 200 3300 or update your details in your Personal Tax Account. They can issue a corrected code to your employer within days. Your next payslip should reflect the change, and any overpayment from previous months may be refunded through your pay.
What if this happened in a previous tax year?
You can claim back overpaid tax for the current year plus the four previous years. HMRC may also identify the issue automatically and send you a P800. See our P800 guide for details.
See also: HMRC Tax Rebate Complete Guide · Nurse Uniform Tax Relief Scenario · Scottish Tax Guide
How to Check Your Tax Code
Checking your tax code is a simple but crucial step in ensuring you’re not overpaying tax. Your tax code appears on your payslip, P60, and in your HMRC online account. If you’ve recently changed jobs, had a change in income, or started receiving benefits like a company car, your tax code may need updating. A common mistake is assuming your employer has applied the correct code — but errors do happen, especially during transitions. If your code starts with ‘BR’, ‘D0’, or ‘D1’, it typically means you’re being taxed at the basic, higher, or additional rates on all income without any personal allowance — which is usually only appropriate if you have multiple jobs or untaxed income. If your code lacks a number (e.g., just ‘K’ or a letter code), it may indicate that your allowances have been reduced or removed. Regularly reviewing your tax code — especially after starting a new job — can help you catch issues early and avoid large tax bills or missed refunds later.
Common Reasons for Incorrect Tax Codes
Incorrect tax codes are surprisingly common — especially during job changes or when personal circumstances shift. One major cause is the delayed or missing P45, as seen in Rachel’s case. Without it, employers must apply an emergency tax code (usually BR, D1, or 1257L on a non-cumulative basis), which can lead to overpayment if not corrected promptly. Another frequent cause is HMRC not being aware of changes like a new job, pension contributions, or benefits-in-kind, which can affect your allowance. Sometimes, multiple jobs can lead to tax codes being split incorrectly across employers, leaving one job taxed at the basic rate while others receive no allowance. Finally, HMRC’s systems occasionally lag in updating personal details, especially if you’ve recently moved or changed your name. If you suspect an issue, checking your tax code via the HMRC app or online account is free and quick, and you can request a tax code review if needed.
How to Claim a Tax Refund for Overpaid PAYE
If you’ve overpaid tax due to an incorrect tax code, HMRC will usually correct the issue automatically in your next payslip if your employer updates your code mid-year. However, if the tax year has ended or you’ve left the job, you may need to claim directly. For overpayments in the current or previous tax year, you can use the HMRC online service or submit form P50 if you’re no longer employed. The process is straightforward: gather your P60, P45, and recent payslips, then either update your tax code via HMRC’s online portal or contact HMRC directly. Most refunds are processed within 4–8 weeks, and you’ll receive the amount via BACS into your bank account. Importantly, you have up to four years from the end of the tax year in which you overpaid to make a claim — so don’t delay. Tools like our tax rebate calculator help you estimate your refund before you apply, so you know exactly what to expect and can verify HMRC’s calculations.
How to Check Your Tax Code
Checking your tax code is a simple but crucial step in ensuring you’re not overpaying tax. Your tax code appears on your payslip, P60, and in your HMRC online account. If you’ve recently changed jobs, had a change in income, or started receiving benefits like a company car, your tax code may need updating. A common mistake is assuming your employer has applied the correct code — but errors do happen, especially during transitions. If your code starts with ‘BR’, ‘D0’, or ‘D1’, it typically means you’re being taxed at the basic, higher, or additional rates on all income without any personal allowance — which is usually only appropriate if you have multiple jobs or untaxed income. If your code lacks a number (e.g., just ‘K’ or a letter code), it may indicate that your allowances have been reduced or removed. Regularly reviewing your tax code — especially after starting a new job — can help you catch issues early and avoid large tax bills or missed refunds later.
Common Reasons for Incorrect Tax Codes
Incorrect tax codes are surprisingly common — especially during job changes or when personal circumstances shift. One major cause is the delayed or missing P45, as seen in Rachel’s case. Without it, employers must apply an emergency tax code (usually BR, D1, or 1257L on a non-cumulative basis), which can lead to overpayment if not corrected promptly. Another frequent cause is HMRC not being aware of changes like a new job, pension contributions, or benefits-in-kind, which can affect your allowance. Sometimes, multiple jobs can lead to tax codes being split incorrectly across employers, leaving one job taxed at the basic rate while others receive no allowance. Finally, HMRC’s systems occasionally lag in updating personal details, especially if you’ve recently moved or changed your name. If you suspect an issue, checking your tax code via the HMRC app or online account is free and quick, and you can request a tax code review if needed.
How to Claim a Tax Refund for Overpaid PAYE
If you’ve overpaid tax due to an incorrect tax code, HMRC will usually correct the issue automatically in your next payslip if your employer updates your code mid-year. However, if the tax year has ended or you’ve left the job, you may need to claim directly. For overpayments in the current or previous tax year, you can use the HMRC online service or submit form P50 if you’re no longer employed. The process is straightforward: gather your P60, P45, and recent payslips, then either update your tax code via HMRC’s online portal or contact HMRC directly. Most refunds are processed within 4–8 weeks, and you’ll receive the amount via BACS into your bank account. Importantly, you have up to four years from the end of the tax year in which you overpaid to make a claim — so don’t delay. Tools like our tax rebate calculator help you estimate your refund before you apply, so you know exactly what to expect and can verify HMRC’s calculations.