An emergency tax code is a temporary code HMRC or your employer uses when they do not yet have enough information to tax you correctly. It usually means you pay too much tax for a short time — sometimes a lot too much — until your record catches up. This guide decodes the four codes people most often see, BR, 0T, D0 and D1, plus the W1/M1 suffix, and explains how to fix them. For the general meaning of the numbers and letters in a code, see Tax Codes Explained.
To check what a specific code does to your pay, use the Tax Code Checker.
1. Why you end up on an emergency code
The most common triggers are:
- Starting a new job without a P45 from your last employer.
- Starting your first job or returning to work after a long break.
- Receiving company benefits or a State Pension that HMRC needs to account for.
- Drawing money from a pension flexibly for the first time.
In each case, the payer does not know your earnings so far this tax year or your remaining tax-free Personal Allowance, so it defaults to a code that errs on the side of collecting tax.
2. The codes, decoded
BR — Basic Rate
A BR code taxes all the income from that source at the basic rate of 20%, with no Personal Allowance applied. BR is normal and correct for a second job or second pension, where your tax-free allowance is already used against your main income. It is a problem only if it is applied to your main or only job.
0T — no allowance, banded rates
A 0T code gives you no Personal Allowance, but unlike BR it applies the normal rate bands (20%, then 40%, then 45%) as your income rises. You typically see 0T when you start a job with no P45 and have not completed a starter checklist, or once your income exceeds £125,140 and your allowance has fully tapered away.
D0 and D1 — higher and additional rate
- D0 taxes all income from that source at the higher rate (40%).
- D1 taxes all income from that source at the additional rate (45%).
These are used where a second source of income sits entirely within your higher- or additional-rate band — common for high earners with a second job or multiple pensions.
W1 and M1 — the “non-cumulative” suffix
A code ending in W1 (weekly) or M1 (monthly) is the true “emergency” version of your normal code. It means tax is worked out on that pay period alone, ignoring what you have earned and paid earlier in the year. So 1257 W1 gives you one week’s slice of the Personal Allowance, but does not reconcile against previous pay. This often leads to overpayment if you started partway through the year, because it does not give back unused allowance from earlier months.
3. How much extra tax does an emergency code cost?
The damage depends on the code. Suppose you earn £3,000 in a month and the correct code would be 1257L (giving roughly £1,048 tax-free that month):
| Code | Monthly tax on £3,000 (approx.) |
|---|---|
| 1257L (correct) | ~£390 |
| 0T M1 | ~£600 |
| BR | £600 (flat 20%) |
| D0 | £1,200 (flat 40%) |
A BR or 0T code can easily cost you £100–£200 extra a month; a D0 code can double your bill.
4. How to fix it and get your money back
- Give your employer your P45 from your previous job, or complete the HMRC starter checklist so they can apply the right code.
- Check your code online via your Personal Tax Account at gov.uk — you can see and query your code there.
- Once HMRC has the full picture, it issues your employer a cumulative code (no W1/M1). The next payslip usually refunds the overpaid tax automatically through PAYE.
- If the tax year has already ended, any overpayment is reconciled and HMRC sends a P800 with a refund.
Check your code now
Don’t assume an unfamiliar code is wrong — but don’t assume it’s right either. Enter your code in the Tax Code Checker to see exactly how it’s taxing you, then model your correct take-home with the Take-Home Pay Calculator.