If your payslip shows a code like 1257 W1/M1, 0T or BR, you've been put on emergency tax. It usually means payroll doesn't yet have the full picture of your tax position — most often because you started a new job without a P45. It's a temporary placeholder, not a penalty, but it can quietly take more tax than you owe. Here's what each code does and how to get back to normal.
The three emergency codes you'll actually see
- 1257 W1/M1 — you still get the full £12,570 Personal Allowance, but on a non-cumulative basis: each pay period is taxed in isolation rather than across the year. Over-deduction here is usually modest.
- 0T — no allowance at all; you're taxed from the first pound, but still stepped through the 20% / 40% / 45% bands. This can cost noticeably more, particularly early in the year.
- BR — a flat 20% on everything under the code, no allowance. Correct on a genuine second job; an over-deduction if it's wrongly applied to your only job.
For how these sit alongside every other code (1257L, K codes, D0/D1, the S/C prefixes), see the full UK tax codes explained guide.
Why payroll puts you on one
Emergency codes fill an information gap. The usual triggers are:
- Starting a new job without handing over a P45 from your last one.
- Not completing HMRC's starter checklist (the form that replaces the old P46).
- Starting a second job or a pension alongside existing income.
- A change in circumstances — for example beginning to receive taxable benefits like a company car.
The non-cumulative catch
The reason an emergency code matters is the W1/M1 mechanism. A normal cumulative code looks at your total pay and total allowance for the year to date and smooths the tax across every payslip — so if you've underused your allowance, you get it back automatically. A W1/M1 code can't do that: it taxes each period as if it were the first of the year, so it never reconciles earlier months on its own. That's exactly the same machinery that makes a one-off bonus look over-taxed in the month it lands.
How to get off emergency tax
- Hand over your P45 from your previous job, or complete the starter checklist so your new employer can request the right code.
- Check your HMRC personal tax account — you can see and update your employment details online, which prompts HMRC to issue a corrected code.
- Give it a payslip or two, then chase HMRC directly if the code still hasn't changed.
Getting your money back
When the correct cumulative code is applied during the same tax year, your next payslip recalculates the whole year and the overpaid tax comes back through your wages automatically — no claim needed. If the code is never corrected, HMRC reconciles your record after 5 April and issues a refund (a P800) on its own, though fixing the code is always faster.
To estimate the gap, drop your salary into the Salary Calculator, switch the tax-code field between 0T (or BR) and 1257L, and compare the take-home figures — the difference is roughly what you're owed.
Emergency tax FAQs
- What is an emergency tax code?
- An emergency tax code is a temporary code payroll uses when it doesn't yet have the full picture of your tax situation — typically a new job with no P45. The common forms are 1257 W1/M1 (the standard allowance but taxed non-cumulatively), 0T (no allowance, taxed through the bands), and BR (a flat 20%). They're meant to be replaced by a normal cumulative code once HMRC has your details.
- Why have I been put on emergency tax?
- Usually because payroll lacks information: you started a new job without handing over a P45, you didn't complete a starter checklist, you've started a second job or a pension, or your circumstances changed (for example you began receiving taxable benefits). It isn't a penalty — it's a placeholder until HMRC issues the correct code.
- Does an emergency tax code mean I'm paying too much tax?
- Often, but not always. 1257 W1/M1 still gives you the tax-free allowance, so the over-deduction may be small. 0T and BR give no allowance, so you can pay noticeably more than you should — especially early in the tax year. Any overpayment is refunded once the correct cumulative code is applied, or after the tax year ends.
- What's the difference between W1/M1 and a cumulative code?
- A cumulative code looks at your total pay and total allowance for the year so far, smoothing tax across every payslip. A W1/M1 (week 1 / month 1) code ignores the year-to-date picture and taxes each pay period in isolation as if it were the first of the year. That's why it can't self-correct earlier over- or under-payments on its own.
- How do I get off emergency tax?
- Give your new employer your P45 from your last job, or complete HMRC's starter checklist so they can apply the right code. If it still hasn't changed after a payslip or two, check and update your details in your HMRC personal tax account or call HMRC. Once a cumulative code is applied, payroll recalculates and any overpaid tax comes back through your next pay.
- Will I get an emergency tax refund automatically?
- Yes, in most cases. When your correct cumulative code is applied during the same tax year, your next payslip recalculates the whole year and refunds the overpayment through your wages. If the code is never corrected, HMRC reconciles it after 5 April and sends a refund (a P800) automatically — though it's faster to fix the code yourself.