Started a new job or taken a pension lump sum and been hit with a strange tax code? Enter your monthly pay and code to see how much extra tax you are paying — and exactly how to get it back from HMRC.
England, Wales & Northern Ireland · 2026/27
Emergency tax is a temporary code your employer or pension provider uses when HMRC has not yet given them your full tax details. It is not a penalty — it is a stop-gap that errs on the side of taking more tax so you do not under-pay. The downside is that, until your real code arrives, your take-home pay can be noticeably lower than it should be.
The most common trigger is starting a new job without a P45, taking a flexible pension lump sum, or having a second source of income. The good news is that an emergency code is almost always corrected automatically once HMRC catches up, and any overpaid tax comes back to you.
| Code | What it does | Allowance |
|---|---|---|
| 1257L W1/M1 | Gives the allowance, but only for the current week/month — not cumulative | £12,570 (split) |
| BR | Taxes every pound at the basic 20% rate | None |
| 0T | No allowance; taxes at 20%, then 40%, then 45% as you cross the bands | None |
The key difference between 1257L W1/M1 and the normal cumulative 1257L is the "Week 1 / Month 1" flag. A cumulative code looks at your pay across the whole year so far and spreads your £12,570 allowance evenly. A W1/M1 code resets every period, so if you started part-way through the year you cannot reclaim the allowance you "missed" in earlier months until the code is corrected.
Illustrative monthly Income Tax on £2,500 gross. BR and 0T cost roughly £209 more per month than the normal code until HMRC updates it.
Suppose you start a new job on £30,000 (£2,500 a month) and are put on a BR code because you had no P45:
Once HMRC issues your correct code, the overpayment is repaid — often as a refund in your very next payslip when a cumulative code is applied.
For a full picture of what your pay should be once the code is corrected, try our salary calculator or the National Insurance calculator.
The standard emergency code is 1257L W1/M1. It still gives the £12,570 Personal Allowance, but only one week or month at a time, so it can't recover allowance from earlier in the year. BR and 0T are used when HMRC has no allowance details at all.
BR taxes every pound at 20% with no allowance. On £2,500 a month that's £500 versus about £291 under the normal cumulative code — roughly £209 more each month until it's corrected.
Usually automatically: give your employer your P45 or a Starter Checklist, and once HMRC issues your real code the overpayment is refunded — often in your next payslip. For pension lump sums use forms P55, P53Z or P50Z.
0T gives no Personal Allowance and taxes income at 20%, 40% and 45% as it crosses the bands. HMRC uses it when you start without a P45 and don't complete a Starter Checklist, or when your allowance is already used elsewhere.