Enter Your Tax Code
| Tax Code | — |
| Code Type | — |
| Region | — |
| Personal Allowance (This Code) | — |
| Standard Allowance (2025/26) | £12,570 |
| Difference from Standard | — |
| Estimated Annual Tax (at this salary) | — |
| vs Standard Code (1257L) | — |
How UK Tax Codes Work
Your tax code is issued by HMRC and tells your employer how much Income Tax to deduct from your pay each month. Understanding what your tax code means is the first step to making sure you're not paying too much — or too little — tax.
The Number: Personal Allowance ÷ 10
The number in most tax codes represents your tax-free personal allowance divided by 10. The standard personal allowance for 2025/26 is £12,570, which gives the number 1257. Your employer multiplies this by 10 to arrive at your annual tax-free amount.
If your number is higher than 1257 (e.g. 1383), HMRC has increased your allowance — perhaps to account for job-related expenses or a higher Marriage Allowance. If it's lower (e.g. 1000), something has reduced your allowance — such as a taxable benefit-in-kind like a company car.
The Letter: What It Tells Your Employer
The letter after the number gives your employer further instructions. The most common letters are:
- L — You're entitled to the standard personal allowance. This is the most common suffix.
- M — You've received the Marriage Allowance transfer from your spouse or civil partner, boosting your allowance by £1,260 to £13,830.
- N — You've transferred part of your personal allowance to your spouse or civil partner under Marriage Allowance, reducing your allowance by £1,260 to £11,310.
- T — HMRC needs to review your tax affairs. This may indicate complex circumstances and your code may change.
- W1, M1 or X — Emergency/non-cumulative basis. Tax is calculated on each pay period in isolation, not cumulatively for the year.
Prefixes: S and C
A prefix of S means you're a Scottish taxpayer. Your income tax is calculated using Scottish Income Tax rates (set by the Scottish Parliament), which differ from the rest of the UK at higher income levels. A prefix of C means you're a Welsh taxpayer — currently Welsh rates mirror the rest of England, so it has no practical difference to your tax bill, but HMRC uses it for record-keeping.
Special Codes: BR, D0, D1, 0T, NT
BR (Basic Rate) means all your income from this source is taxed at 20% — you receive no personal allowance for this employment. This is commonly applied to second jobs. D0 applies 40% to all income, and D1 applies 45%. 0T gives you no personal allowance but still applies progressive tax rates. NT means no tax is deducted at all — a rare code used for specific exempt payments.
K Codes: Negative Allowance
A K code (e.g. K500) is used when you have untaxed income that exceeds your personal allowance — for example, unpaid tax from a previous year, or the value of taxable benefits exceeds your allowance. Instead of reducing your taxable income, the K number is added to it. K500 means an additional £5,000 is added to your taxable income on top of your salary. There is a limit on how much extra tax can be collected this way: no more than 50% of your gross pay in any single pay period.
Emergency Tax Codes: W1/M1/X
If you start a new job without a P45 from your previous employer, HMRC may issue an emergency tax code. These are often shown as 1257L W1, 1257L M1, or simply X. The key difference is that tax is calculated on a non-cumulative basis — each pay period is treated independently, rather than looking at your cumulative earnings across the whole year. This can lead to overpayment of tax, which HMRC typically corrects automatically through a P800 adjustment at the end of the tax year.
Common Tax Codes Reference Table
A quick guide to the most frequently encountered UK tax codes and what they mean.
| Code | What It Means | Personal Allowance |
|---|---|---|
| 1257L | Standard 2025/26 — full personal allowance, employed in England/Wales/NI | £12,570 |
| BR | Basic rate only — no personal allowance. Typically second job or allowance used elsewhere | £0 |
| D0 | Higher rate (40%) on all income — no personal allowance | £0 |
| D1 | Additional rate (45%) on all income — no personal allowance | £0 |
| 0T | No personal allowance, progressive rates apply — new starter without P45 or allowance exhausted | £0 |
| NT | No tax deducted — exempt payments (rare) | N/A |
| S1257L | Scottish taxpayer with standard allowance | £12,570 |
| C1257L | Welsh taxpayer with standard allowance (same rates as England) | £12,570 |
| 1257M | Marriage Allowance received — allowance boosted by £1,260 | £13,830 |
| 1257N | Marriage Allowance transferred away — allowance reduced by £1,260 | £11,310 |
| 1257T | HMRC review needed — same allowance but code under review | £12,570 |
| K[number] | Negative allowance — taxable income is increased by (number × 10). For unpaid tax or excess benefits | Negative |
| [code] W1/M1 | Emergency — non-cumulative. Tax calculated on this period only, not cumulatively | As coded |
| 1257L X | Emergency code, week/month basis not specified — non-cumulative | £12,570 |
Watch Out For These Situations
If you're on a BR tax code but this is your only (or main) employment, you're losing your entire personal allowance — meaning you're paying 20% tax on every pound you earn. Contact HMRC online via your Personal Tax Account or call 0300 200 3300 to have your code corrected. You may be owed a refund.
An emergency tax code (shown as W1 or M1 after your code) means tax is calculated as if every pay period is the first of the year — not cumulatively. If you started a new job part-way through the tax year, you may be paying too much tax in those early months. HMRC usually corrects this automatically with a P800 tax calculation after the year ends, but you can contact HMRC to request an in-year correction rather than waiting.
HMRC rules prevent a K code from taking more than 50% of your gross pay in any single pay period, no matter how large the K number. This protects employees from having most of their pay deducted in a single period. If your K code is very large, unpaid tax may be collected over several years.