Tax Code 1257L Explained: What It Means and Why You Have It
Your tax code tells your employer how much income to treat as tax-free before deducting income tax through PAYE. In 2025-26, the most common tax code in the UK is 1257L — held by the majority of employees with one job and no unusual tax circumstances. Here is how to read it.
How to decode 1257L
Tax codes are made up of a number and a letter:
- 1257 — represents your tax-free amount. Multiply by 10 to get the actual figure: 1257 × 10 = £12,570 (the Personal Allowance for 2025-26).
- L — means you are entitled to the standard Personal Allowance.
So 1257L simply means: "This person has a standard Personal Allowance of £12,570."
Other common tax code letters
| Letter | Meaning |
|---|---|
| L | Standard Personal Allowance |
| M | Marriage Allowance received (allowance is 1,383 rather than 1,257) |
| N | Marriage Allowance transferred to spouse |
| T | HMRC needs to review your tax code (various reasons) |
| BR | All income taxed at Basic Rate — typically a second job or pension |
| D0 | All income taxed at Higher Rate — second job above £50,270 |
| D1 | All income taxed at Additional Rate (45%) |
| K | Negative allowance — you owe more tax than your allowance covers (e.g. large company car benefit) |
| NT | No tax to be deducted |
1257L W1/M1: the emergency tax code
You may see your code followed by W1 (week 1) or M1 (month 1). This means HMRC is applying your tax code on a non-cumulative basis — i.e., each pay period is treated in isolation, without accounting for tax paid so far in the year. This often happens when you start a new job without providing a P45.
The result is that you may overpay or underpay tax during the year. Once HMRC has verified your details and applied the correct cumulative code, any overpayment is refunded through PAYE automatically.
If 1257L appears on a second job
Having 1257L on a second job is almost always wrong. Your Personal Allowance is allocated to your main job. Your second job should carry a BR (20%) or D0 (40%) code. If a second employer is using 1257L, you will underpay tax and receive a bill at year end. Contact HMRC immediately to correct this.
How to check and change your tax code
- Sign into your HMRC Personal Tax Account at www.gov.uk/personal-tax-account
- Call HMRC on 0300 200 3300
- Check your payslip — your employer must show your current tax code
If your code is wrong, HMRC will update it and notify your employer. Any tax over- or underpaid during the year is corrected automatically through PAYE or a P800 letter after the tax year ends.
Frequently asked questions
Why does my tax code start with S or C?
S at the start (e.g. S1257L) means you are a Scottish taxpayer — your income is taxed using the Scottish rate bands. C at the start (e.g. C1257L) means you are a Welsh taxpayer. The number and letter still work the same way.
My tax code changed mid-year — is that normal?
Yes. HMRC updates codes throughout the year as it receives new information — for example, if you start receiving a company car benefit, change jobs, or begin receiving a state pension. Your employer is notified automatically via a P9 coding notice.
What if I think my tax code is wrong?
Check your Personal Tax Account online first to see why HMRC has issued your code. If something is incorrect — for example, HMRC has included a benefit in kind you no longer receive — you can ask HMRC to revise it. Corrections are applied to future pay periods, and any overpaid tax is refunded.