Tax code Emergency codes (1257L W1/M1/X) explained
Non-cumulative temporary code — each payday taxed in isolation. Here's exactly what it means for your payslip in 2026/27, who should have it, and what to do if it looks wrong.
What Emergency codes (1257L W1/M1/X) means
1257L W1 (week 1), M1 (month 1) or X are emergency tax codes. You still get the standard allowance, but it's applied non-cumulatively: each payday is taxed as if it were the first of the year, ignoring what you've earned or paid so far.
This usually produces roughly correct tax if your pay is steady, but overtaxes you after gaps in employment (you don't get the unused allowance from the missed months) and can undertax after high early-year earnings.
Who gets Emergency codes (1257L W1/M1/X)?
New starters without a P45, people returning to work after a break, those switching from self-employment to PAYE, and anyone starting to draw a pension while working.
What you'd pay on Emergency codes (1257L W1/M1/X)
| Salary | Income tax | Take-home* | vs standard 1257L |
|---|---|---|---|
| £22,000 | £1,886 | £19,360 | — |
| £30,000 | £3,486 | £25,120 | — |
| £40,000 | £5,486 | £32,320 | — |
| £55,000 | £9,432 | £42,457 | — |
| £80,000 | £19,432 | £56,957 | — |
*After income tax and employee National Insurance, 2026/27 rates, England/Wales/NI bands.
What you should do
Give your new employer your P45 or complete the starter checklist promptly. The code normally corrects automatically within a payslip or two once HMRC processes your details; any overpaid tax comes back through your next payslips in the same tax year.
Frequently asked questions
What does tax code Emergency mean?
Non-cumulative temporary code — each payday taxed in isolation. 1257L W1 (week 1), M1 (month 1) or X are emergency tax codes. You still get the standard allowance, but it's applied non-cumulatively: each payday is taxed as if it were the first of the year, ignorin
Is tax code Emergency wrong?
Give your new employer your P45 or complete the starter checklist promptly. The code normally corrects automatically within a payslip or two once HMRC processes your details; any overpaid tax comes back through your next payslips in the same tax year
Who gets tax code Emergency?
New starters without a P45, people returning to work after a break, those switching from self-employment to PAYE, and anyone starting to draw a pension while working.