What W1, M1 and X mean
| Ending | Used when |
|---|---|
| W1 | You're paid weekly, for example 1257L W1 |
| M1 | You're paid monthly, for example 1257L M1 |
| X | Your pay dates vary |
Emergency tax rate: is there one?
There is no separate emergency tax rate. You pay the normal Income Tax rates for your part of the UK; what changes is that each payment is taxed on its own, as if you'd earn the same every week or month, with that period's share of the tax-free amount in your code. GOV.UK warns this could mean you pay the wrong amount of tax.
| Code | Paid | How the tax on each payment is worked out |
|---|---|---|
| 1257L W1 | Weekly | One week's share of the £12,570 tax-free amount, then the normal rates on the rest of that week's pay; earlier weeks are ignored |
| 1257L M1 | Monthly | One month's share (£12,570 ÷ 12 = £1,047.50), then the normal rates on the rest of that month's pay; earlier months are ignored |
| 1257L X | Pay dates vary | Same non-cumulative basis, for the period each payment covers |
| NONCUM on the payslip | Any | Some payroll software prints NONCUM instead of W1, M1 or X; it means the same |
Why it can cost you
Normally PAYE is cumulative: it looks at all your pay and tax since 6 April, so an underpayment in one month is caught up and an overpayment is refunded. On W1 or M1, each payment stands alone, so nothing earlier is taken into account.
Example: paid £3,000 in month 6 on 1257L M1, the tax is £390.20, exactly as if it were month 1. On cumulative 1257L, with the same pay every month so far, it would be £391.00, because the year-to-date figures are used.
How to get off an emergency code
- Give your new employer your P45 from your last job, if you have it.
- HMRC usually sends an updated code once it has your details, which GOV.UK says can take up to 35 days.
- If it's still wrong after that, update your details through your HMRC online account.
Questions
Do I get my money back after an emergency tax code?
If you paid too much, it's usually refunded through your pay once you're on a normal cumulative code, or by HMRC after the tax year.
What is the emergency tax rate?
There isn't a special rate. An emergency code taxes each payment at the normal rates, but on that week's or month's pay alone, so the tax can be too high or too low until HMRC sends your normal code.
Is 1257L M1 an emergency tax code?
Yes. Any code ending in W1, M1 or X is on an emergency (non-cumulative) basis.
Sources
- GOV.UK — Tax codes: emergency tax codes
- HMRC — Specification for PAYE Tax Table Routines, version 24.0
Official sources checked 13 October 2026. This guide explains how pay documents work; it is not tax or legal advice.
