How HMRC Tax Codes Work
A tax code is a combination of numbers and letters that tells your employer how much tax-free income you’re entitled to. The most common code is 1257L, which gives you the standard £12,570 Personal Allowance.[1]
Reading Your Tax Code
The number is your tax-free allowance divided by 10. The letter tells HMRC how to adjust it:[1]
| Letter | Meaning |
|---|---|
| L | Standard Personal Allowance |
| M | You’ve received Marriage Allowance transfer from your partner |
| N | You’ve transferred Marriage Allowance to your partner |
| T | Includes other calculations (e.g. income over £100,000) |
| K | You have deductions that exceed your allowance (tax is added, not subtracted) |
| BR | All income taxed at basic rate (20%) — no tax-free allowance |
| D0 | All income taxed at higher rate (40%) |
| D1 | All income taxed at additional rate (45%) |
| NT | No tax to be deducted |
| 0T | No tax-free allowance — used when HMRC has no information |
Common Tax Codes
- 1257L — the standard code for most employees (2025/26)
- 1282L — includes Blind Person’s Allowance on top of Personal Allowance
- BR — often used for a second job where your allowance is used elsewhere
- K codes — used when you owe tax from a previous year being collected through your code, or have taxable benefits exceeding your allowance
Emergency Tax Codes
If your employer doesn’t have your tax code (e.g. when you start a new job), they’ll use an emergency code. This is usually 1257L on a non-cumulative basis (shown as 1257L W1 or 1257L M1).[3]
Emergency codes may mean you pay too much or too little tax initially. It’s corrected once HMRC issues the proper code.
If Your Tax Code Is Wrong
Check your tax code in your Personal Tax Account on GOV.UK. If it looks wrong:[2]
- Update your details online (e.g. income from a second job, benefits in kind)
- Contact HMRC if you think there’s an error
- HMRC will issue a corrected code to your employer
If you’ve been on the wrong code, you may be due a tax refund.
Scottish & Welsh Tax Codes
If you live in Scotland, your code starts with S (e.g. S1257L). If you live in Wales, it starts with C (e.g. C1257L). This ensures the correct devolved rates apply.[4]
Frequently Asked Questions
What does tax code 1257L mean?
Tax code 1257L is the standard code for most employees. The number 1257 represents your £12,570 Personal Allowance (divided by 10), and the letter L means you are entitled to the standard Personal Allowance.
What is an emergency tax code?
An emergency tax code (shown as 1257L W1 or 1257L M1) is used when your employer does not yet have your correct code. It may result in over- or under-deduction of tax, which is corrected once HMRC issues the proper code.
How do I check if my tax code is correct?
Check your tax code in your Personal Tax Account on GOV.UK. If it appears wrong, update your details online or contact HMRC, who will issue a corrected code to your employer.
What does a K tax code mean?
A K code means your deductions (such as tax owed from a previous year or taxable benefits) exceed your tax-free allowance. Your employer adds tax rather than subtracting a tax-free amount from your earnings.
Further Reading
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Sources
- Tax codes — GOV.UK
- Check your Income Tax — GOV.UK
- Emergency tax codes — GOV.UK
- Income Tax rates and Personal Allowances — GOV.UK