Your tax code is one of the most important numbers on your payslip, yet many employees don’t fully understand what it means or how it affects their take-home pay. Your tax code determines how much income tax your employer deducts from your salary each month. Getting it wrong could mean you’re overpaying or underpaying tax.
This comprehensive guide explains what tax codes are, how they work, and what to do if you think yours is incorrect.
What Is a Tax Code?
A tax code is a series of numbers and letters that HMRC provides to your employer to tell them how much income tax to deduct from your pay. Your employer uses your tax code to calculate the correct amount of tax to withhold from your salary. Understanding your tax code is essential because it directly impacts how much money you take home each month.
How Tax Codes Work
The number in your tax code represents your Personal Allowance, divided by 10. Your Personal Allowance is the amount of income you can earn before paying any tax. For the 2025/26 tax year, the standard Personal Allowance is £12,570. The letter in your tax code tells your employer how to calculate your tax, based on your circumstances.
For example, if your tax code is 1257L, this means you have a Personal Allowance of £12,570 (1257 × 10) and the ‘L’ indicates you’re entitled to the standard Personal Allowance. Your employer uses this information to work out how much tax to deduct from your pay each week or month.
Most Common Tax Codes and What They Mean
Different tax codes apply to different circumstances. Here are the most used ones:
| Tax Code | What It Means |
|---|---|
| 1257L | Standard code – personal allowance of £12,570 |
| BR | All income taxed at basic rate (20%) – usually a second job |
| D0 | All income taxed at higher rate (40%) |
| D1 | All income taxed at additional rate (45%) |
| NT | No tax is deducted from this income |
| 0T | No personal allowance – used when allowance is used up |
| K codes | You owe more tax than your allowance covers (e.g. company benefits) |
| S prefix | Scottish taxpayer – Scottish income tax rates apply |
| C prefix | Welsh taxpayer – Welsh income tax rates apply |
| W1 or M1 | Emergency tax code – calculated on a non-cumulative basis |
Where to Find Your Tax Code
You can find your tax code in several places:
- Your payslip – listed clearly at the top or in the tax section
- Your P60 (end of year) – shows the tax code used during that year
- Your P45 (when leaving a job) – shows the code used by that employer
- Your HMRC online account – go to ‘Check your income tax’ section
- Your HMRC coding notice (P2) – HMRC sends this if your code has changed
Think your tax code might be wrong? EVLAteam can check your tax position and make sure you’re not overpaying. Request a free quote.
What to Do If Your Tax Code Is Wrong
If you believe your tax code is incorrect, the first step is to verify what it should be. Check your HMRC online account and compare it with the code on your payslip.
If your code is definitely wrong, contact HMRC immediately. You can do this through your HMRC online account, by phone, or by post. Explain the discrepancy and provide supporting evidence if necessary. HMRC will typically correct your code within a few weeks, and you’ll usually receive a refund of any overpaid tax through your payroll.
If you’ve been underpaying tax, you may owe money to HMRC. However, if the error was HMRC’s fault, they typically cannot recover money from more than four years ago. Keep records of all correspondence with HMRC regarding your tax code.
Emergency Tax Codes
An emergency tax code (W1, M1, or X) is used when HMRC doesn’t have enough information to calculate your normal code. This commonly happens when you start a new job and your previous employer hasn’t submitted the necessary information to HMRC.
If you’re on an emergency code, it’s usually temporary. Once HMRC receives information about your previous employment or circumstances, they’ll issue you with a permanent code and process any tax refunds due. Always follow up if you’re on an emergency code for more than a few months, as you may be eligible for a refund.
How Company Benefits Affect Your Tax Code
Company benefits (called Benefits in Kind or BIK) can affect your tax code. If your employer provides benefits such as a company car, private medical insurance, gym membership, or phone, the taxable value of these benefits is added to your income for tax purposes. This reduces your Personal Allowance, which is reflected in your tax code.
For example, if a company car is worth £3,000 in taxable benefit, your Personal Allowance would be reduced from £12,570 to £9,570, and your tax code would change accordingly. These details are recorded on your P11D form at the end of the tax year. Check your P11D to see what benefits have been assessed as taxable.
Tax Code Changes
HMRC changes tax codes when your circumstances change. Common reasons for changes include: starting or leaving employment, marriage allowances, significant changes in income, company benefits being added or removed, or changes to tax allowances (such as at the start of a new tax year).
HMRC will notify you of a code change by sending a coding notice (P2) or through your online account. Always check these notifications carefully and contact HMRC if you disagree with any changes. You have the right to appeal if you believe your code is incorrect.
Conclusion
Understanding your tax code is a crucial part of managing your finances effectively. By knowing what your code means and checking it regularly, you can ensure you’re paying the right amount of tax and spot errors before they become problems. Whether you’re employed, have multiple jobs, or receive benefits, your tax code plays a vital role in how much tax you pay.
For more information about tax codes and how they affect your specific situation, visit the HMRC website or speak to a tax professional. Services like Self-Assessment returns, Payroll planning, Accounting support, and Tax Consultancy can all help you optimise your tax position.
Understanding your tax code is just the start. EVLAteam provides comprehensive tax and accounting services to keep your finances in order. Contact us today.
