Emergency tax code
UK tax glossary · Last reviewed: April 2026
Emergency codes like 1257L W1/M1 or BR are non-cumulative — tax is calculated per pay period without considering earlier earnings or the balance of your annual allowance. This often causes overpayment.
You are most likely to receive an emergency code when starting a new job without a P45, returning to work after a gap, or starting to receive a pension. The code should be corrected automatically once HMRC updates your record via the new employer's RTI submission.
Do not wait passively. Give your new employer your P45 or complete a new Starter Checklist (formerly P46). Alternatively, update your tax code directly via your Personal Tax Account at gov.uk.
Worked example
Monthly pay: £3,000. Under correct 1257L code: monthly tax ≈ £246. Under BR emergency code: tax = £3,000 × 20% = £600/month. Overpayment: £354/month. Resolved at year-end via P800, or immediately via Personal Tax Account.
Common questions
How long does it take for an emergency code to be corrected?
Usually 1–3 payroll cycles once HMRC receives your new employer's RTI filing or you submit an update via your Personal Tax Account.
Will I get a refund for the extra tax paid under an emergency code?
Yes. Once the correct code is applied, your employer adjusts deductions to account for the over-payment. If not corrected before year-end, HMRC issues a P800 and refunds automatically.
Related resources
TaxHelper provides general information based on published HMRC rates and guidance. It is not regulated financial or tax advice. For decisions involving significant sums, complex circumstances, or if you are unsure, speak to a qualified accountant or HMRC directly.