Your tax code is the short string of letters and numbers on your payslip — and it quietly decides how much of your salary reaches your bank account every month. Most UK employees see 1257L and never think about it again. But if your code is wrong, you could be paying hundreds of pounds too much (or too little) without realising. Here's what every common code means under 2026/27 rules, using the same maths as our UK salary calculator.
What does tax code 1257L mean?
A standard code is number + letter. The number comes from your tax-free personal allowance: it's your allowance with the last digit dropped. With a £12,570 allowance, that becomes 1257 — and the L means you're entitled to the standard allowance. Multiply the number by 10 and you get your tax-free pay for the year: 1257 → £12,570.
What do BR, D0, D1, 0T and K tax codes mean?
| Code | Meaning | Tax-free pay |
|---|---|---|
| 1257L | Standard employee — full personal allowance | £12,570 |
| BR | Basic rate 20% on everything — usually a second job | £0 |
| D0 | Higher rate 40% on everything | £0 |
| D1 | Additional rate 45% on everything | £0 |
| 0T | No allowance — but normal bands apply (often after BR ends) | £0 |
| K + number | Allowance is negative — e.g. K497 adds £4,970 to your taxable pay | −varies |
| NT | No tax taken at all (rare) | n/a |
What is emergency tax? W1, M1 and X explained
If your payslip code ends in W1 (week 1) or M1 (month 1), you're on a non-cumulative basis: each pay period is taxed on its own, with no memory of what you've earned before. That's why emergency tax usually overcharges people mid-year and only sorts itself out after a refund or year-end reconciliation. The X suffix works the same way for people paid irregularly. When HMRC catches up with your real details, the code drops the suffix and you're back to normal.
What do S and C prefixes mean? Scottish and Welsh tax codes
- C1257L — C is Wales: same allowance, Welsh rates of income tax (currently aligned with England).
- S1257L — S is Scotland: different bands — 19% starter rate, then 20%, 21%, 42% and 45%. A Scottish basic-rate taxpayer pays slightly less; higher earners pay more.
- No prefix — England and Northern Ireland.
Why is my tax code wrong? Common mistakes and what they cost
Three classic situations:
- Started a new job and HR used your P45 incorrectly — you land on 0T or BR until HMRC updates. On a £40,000 salary, a month on BR costs about £210 extra.
- Two jobs — your second job has no allowance, so it's taxed at 20%+ from the first pound. Deliberate, but check the split is right if your second job pushes into 40%.
- Company benefits — a £12,000 company car can shrink your code to something like 457L, and the high-income child benefit charge can turn 1257L into a reduced or K code.
A single wrong digit changes your tax by roughly £10 per point of allowance, per month, at basic rate. Over a year that's real money.
How do I check and fix my tax code?
Use HMRC's Check your Income Tax service in your Personal Tax Account, or the HMRC app. Your employer can't change the code themselves — only HMRC can. If it's wrong, the online service lets you report it, the corrected code reaches your employer's payroll within days, and any refund is usually paid automatically in the next payslip.
Frequently asked questions
Is 1257L a good tax code?
Yes — 1257L is the standard 2026/27 code. It means you get the full £12,570 personal allowance and normal tax bands. Most employees should be on it.
Why am I on BR tax code with one job?
BR means your employer has no tax details for you — usually a missing or late P45. HMRC normally fixes it within weeks; chase them via your Personal Tax Account if a second payslip still shows BR.
Does a W1 or M1 code mean I lose money?
Usually you overpay during the year, not underpay. Emergency tax ignores previous earnings, so you can't use up your allowance gradually. Any overpayment is refunded automatically once the correct code applies.
What is the difference between 0T and BR tax codes?
BR taxes every pound at 20%. 0T gives no allowance but uses normal bands — so part of your pay is taxed at 20% and anything above the basic threshold at 40%. On higher salaries 0T usually costs more than BR.
How much is my pay after tax?
We have worked take-home examples for common salaries: £30,000, £40,000, £45,000, £50,000 and £55,000 after tax — or enter your exact pay and student-loan status into the UK salary calculator for a full breakdown of income tax, National Insurance and net pay.