If you open your payslip, there is a small box with a tax code on it. For most people in the UK that code is 1257L. It looks random, but every character has a meaning, and understanding it can save you money.
What the number means
The number 1257 comes from the standard personal allowance of £12,570. HMRC drops the final zero, so 12,570 becomes 1257. This is the amount you can earn each tax year before income tax applies.
If HMRC changes your allowance — for example to recover unpaid tax, or to account for work benefits — the number goes down. If you have more allowance than usual, such as Marriage Allowance or expenses relief, the number goes up.
What the letter means
The letter L means you are entitled to the standard personal allowance. There are other letters too: M means you have received Marriage Allowance from your partner, N means you have given it to them, T shows that HMRC is making other calculations, and BR, D0, and D1 mean every pound of that income is taxed at a fixed rate.
How it is used in real life
Employers use your tax code to work out how much tax to take from each payday. If your code is 1257L and your salary is £35,000 for 2026/27, you pay no tax on the first £12,570, and 20 per cent on the rest, which is £4,486. Spread across twelve months, that is about £373 a month.
You can see the same calculation live using our salary calculator.
When 1257L is wrong
1257L is the default but not universal. You should not be on 1257L if:
- You have a second job that should usually be on BR.
- You receive work benefits such as a company car or private medical insurance.
- You owe HMRC tax from a previous year.
- You have claimed Marriage Allowance (you should be on 1131N or 1383M).
If you think your code is wrong, check it in your Personal Tax Account, then use our tax code calculator to see what the take-home pay should look like.
The bottom line
1257L is simply "you get the full standard allowance and nothing unusual is happening." If anything ever changes — a second job, a benefit in kind, or a bonus that pushes you into a higher band — check the code matches. It is the single quickest way to spot PAYE mistakes.