Your tax code tells your employer or pension provider how much Income Tax to take from your pay. When it is wrong, you can overpay for months without noticing, or end up with a bill from HMRC. This guide explains what 1257L means, why you might see W1, M1 or X after it, and what to do if your code looks wrong.
The short version
- 1257L is the standard code for most people in 2026/27. It reflects the £12,570 Personal Allowance.
- A code ending in W1, M1 or X, or “NONCUM” on your payslip, means you are on an emergency tax code.
- Emergency codes usually follow a new job. HMRC normally sorts them out within 35 days once it has your details.
- If your code is still wrong after that, you can update it through HMRC’s Check your Income Tax service, and any overpaid tax comes back through your pay.
What 1257L actually means
For 2026/27, which runs from 6 April 2026 to 5 April 2027, the standard Personal Allowance is £12,570. The 1257 reflects that £12,570, and the L means you get the standard allowance.
On a monthly payroll, roughly £1,048 of each month’s pay is tax-free. Above the allowance, income is taxed at 20% up to £50,270, 40% up to £125,140 and 45% above that (Scotland has its own rates). The allowance is reduced by £1 for every £2 of adjusted net income over £100,000, so it disappears entirely at £125,140.
You get one tax code for each job or pension. If you have two jobs, normally only one of them carries your allowance, and the second will often be on BR.
What the letters mean
| Code or letter | What it means |
|---|---|
| L | You get the standard tax-free Personal Allowance |
| M | You receive 10% of your partner’s Personal Allowance through Marriage Allowance |
| N | You have transferred 10% of your Personal Allowance to your partner |
| T | Your code includes other calculations to work out your Personal Allowance |
| K | You have untaxed income or deductions higher than your Personal Allowance |
| S or C (at the start) | Your income is taxed using Scottish (S) or Welsh (C) rates |
| 0T | Your allowance has been used up, or you have started a new job and your employer does not have the details they need |
| BR | All income from this job or pension is taxed at the basic rate |
| D0 / D1 | All income from this source is taxed at the higher rate (D0) or additional rate (D1) |
| NT | You are not paying any tax on this income |
| W1, M1 or X | You are on an emergency tax code |
A K code often reflects a company car, State Pension or tax owed from an earlier year. Your employer cannot take more than half of your pre-tax pay when using a K code.
Emergency tax codes: W1, M1 and X
An emergency code is a temporary code used when your employer does not yet have details of your income earlier in the tax year. W1 is used for weekly pay, M1 for monthly pay and X where pay dates vary. You might see it written as 1257L M1, or with NONCUM on your payslip, depending on the payroll software.
A normal code is cumulative: each payday looks at your pay and tax for the whole year to date, so any allowance you have not used catches up automatically. An emergency code is non-cumulative: tax is worked out on that week’s or month’s pay only. If you had little or no income earlier in the year, that usually means you pay too much.
Worked example: starting a job part way through the year
Emma has had no income since 6 April 2026. She starts a new job in October on a salary of £36,000, paid £3,000 a month. She has no P45, and her employer puts her on 1257L M1.
- On the emergency code, each payday only gives her one month’s worth of allowance, about £1,048. She pays 20% on roughly £1,952, which is about £390 a month.
- On a normal cumulative 1257L code, by October payroll counts seven months of allowance, about £7,337, against her £3,000 of pay to date. She pays no tax at all that month.
Across the full year Emma earns £18,000. Her correct bill is 20% of £5,430 (£18,000 less £12,570), which is £1,086. If she stayed on the emergency code from October to March she would pay about £2,343, an overpayment of roughly £1,257.
Once HMRC issues a cumulative code, the payroll recalculates from the start of the year and the excess comes back in her pay.
How to fix a wrong tax code
- Hand over your P45. If you have one from your previous job, give it to your new employer. If not, fill in the starter checklist they give you.
- Give HMRC time. HMRC usually updates your code once it gets details from your new and previous employers. This can take up to 35 days from when you start.
- Check your code online. If it still looks wrong, sign in to HMRC’s Check your Income Tax service and review the employment, pension, estimated income, company benefit and expenses details HMRC holds. Correct anything that is out of date.
- Watch your payslip. HMRC will tell you and your employer the new code within 15 working days. If you are paid monthly, it should appear on your next or the following payslip. If you are paid weekly, it should be on your third payslip.
Where you have overpaid, HMRC asks your employer to refund the difference through your pay. Where you have underpaid, HMRC will usually adjust your code to collect it over one or more tax years where possible.
Common mistakes we see
- Not checking the first payslip in a new job. Emergency codes are easy to spot.
- Leaving an estimated income figure out of date. HMRC bases your code on its estimate of your income, so a pay rise or reduced hours can throw it off.
- Two jobs, both on 1257L. That gives you the allowance twice and leads to an underpayment.
- Ignoring benefits in kind. A new company car or medical cover should reduce your code. If it does not, tax builds up.
Questions and answers
What does 1257L mean in 2026/27?
It means you get the standard £12,570 tax-free Personal Allowance from that job or pension, with the rest of your pay taxed at the normal rates.
How long will I be on an emergency tax code?
HMRC usually updates it once it has details from your new and previous employers, which can take up to 35 days from when you start. If it is still wrong after that, update it through HMRC’s online service.
Will I get back tax I overpaid on an emergency code?
Yes. Once your code is corrected, HMRC asks your employer to refund the difference through your pay. If that does not happen before the tax year ends, HMRC checks your tax afterwards and writes to you if you have paid the wrong amount.
Why is my second job on BR?
Your allowance is normally used against your main job, so income from a second job is taxed at the basic rate. If your main job pays less than £12,570, update your income details through HMRC’s Check your Income Tax service so both codes reflect what you actually earn.
Want us to check your tax code?
If your payslip shows W1, M1, X, 0T or a K code and you are not sure why, we can check it and deal with HMRC for you. Bring your latest payslip and any coding notice: book a free consultation. Prefer to talk? Call or WhatsApp us on 01444 300981.
You can also see what your take-home pay should look like with our free net pay calculator.
Sources
- GOV.UK: Tax codes
- GOV.UK: What your tax code means
- GOV.UK: Emergency tax codes
- GOV.UK: If you think your tax code is wrong
- GOV.UK: If you’ve paid too much or too little tax
- GOV.UK: Why your tax code might change
- GOV.UK: If you have a K in your tax code
- GOV.UK: Income Tax rates and Personal Allowances
This guide is general information based on the rules for the 2026/27 tax year and is not personal advice. Your own position depends on your full circumstances.