Tax Code Checker
Decode your HMRC tax code and understand exactly what it means for your tax. Enter your tax code to see a plain-English explanation and your estimated income tax.
Key Takeaway
Your tax code tells your employer how much tax to deduct. The most common code is 1257L, which gives you a £12,570 tax-free Personal Allowance.
Key Facts
Standard Code
1257L
S Prefix
Scottish rates
K Prefix
Extra tax owed
W1/M1
Emergency code
You are entitled to the standard tax-free Personal Allowance. This is the most common tax code suffix.
Your tax-free Personal Allowance is £12,570.
Personal Allowance
£12,570
| Code | Description |
|---|---|
| The most common tax code for 2024-25 onwards, reflecting a Personal Allowance of £12,570. | |
| Scottish version of the standard code — same allowance, different tax rates. | |
| Welsh version of the standard code. | |
| Basic rate — typically used for a second job. | |
| K code — £4,750 is added to your taxable income (e.g., company car benefit). | |
| Emergency tax code — temporary, non-cumulative basis. |
How Tax Codes Work
Your HMRC tax code is used by your employer or pension provider to calculate how much income tax to deduct from your pay. The code is made up of numbers and letters that together determine your tax-free amount and the rates applied.
The numbers in your tax code represent your tax-free Personal Allowance. Multiply the number by 10 to get your allowance. For example, the number 1257 means a Personal Allowance of £12,570. This is the amount you can earn before paying income tax.
The letters tell your employer about your situation and which tax rates to use. The most common suffix is L, which means you are entitled to the standard Personal Allowance. Prefixes like S (Scottish) or C (Welsh) indicate which country’s tax rates apply.
K codes work differently. Instead of giving you a tax-free amount, the number is added to your taxable income. This happens when you have untaxed income (such as company benefits) that exceeds your Personal Allowance. For example, K475 means £4,750 is added to your taxable income.
An emergency tax code (indicated by W1, M1, or X after your code) means HMRC does not have enough information to give you a correct code. Each pay period is taxed independently rather than cumulatively, which often results in overpayment. Contact HMRC to resolve this.
Tax Code Letters Explained
| Letter | Type | Meaning |
|---|---|---|
| L | Suffix | Standard tax-free Personal Allowance |
| M | Suffix | Marriage Allowance recipient (10% of partner’s allowance transferred to you) |
| N | Suffix | Marriage Allowance transferor (you transferred 10% of your allowance) |
| T | Suffix | HMRC needs to review your tax code |
| S | Prefix | Scottish Income Tax rates apply |
| C | Prefix | Welsh Income Tax rates apply |
| K | Prefix | Income not taxed another way exceeds your allowances |
| BR | Special | All income taxed at basic rate (20%) |
| D0 | Special | All income taxed at higher rate (40%) |
| D1 | Special | All income taxed at additional rate (45%) |
| NT | Special | No tax deducted |
| 0T | Special | No Personal Allowance — all income taxed through bands |
Frequently asked questions
What does my tax code mean?
Your tax code tells your employer how much tax-free income you are entitled to. The numbers represent your Personal Allowance divided by 10, and the letters indicate your situation. For example, 1257L means you have a £12,570 Personal Allowance with standard conditions.
What is the most common UK tax code?
The most common UK tax code is 1257L. This gives you the standard Personal Allowance of £12,570 for the 2025-26 tax year. The L suffix means you are entitled to the standard tax-free allowance with no special circumstances.
What does a K tax code mean?
A K code means you have income that is not being taxed another way (such as company benefits) and it exceeds your Personal Allowance. Instead of receiving a tax-free amount, the K number is multiplied by 10 and added to your taxable income. For example, K475 adds £4,750 to your taxable income.
What is an emergency tax code?
An emergency tax code (shown with W1, M1, or X suffix) is a temporary code HMRC applies when they do not have enough information about your income. It taxes you on a non-cumulative basis — each pay period is treated independently. You may overpay tax on an emergency code. Contact HMRC to get your correct code.
Why has my tax code changed?
HMRC may change your tax code if your circumstances change — for example, if you start receiving a company benefit, change jobs, start a second job, or your estimated income changes. You will receive a PAYE coding notice (P2) explaining the change. If you think your code is wrong, contact HMRC.
Sources
Related Calculators
Last updated March 2026. Reflects 2025-26 tax year rates.
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