You have started a new job, checked your first payslip, and the tax deduction is far higher than expected. You have probably been put on an emergency tax code. This is temporary, usually fixes itself, and you will get the overpaid tax back. Here is exactly what to do.
What is an emergency tax code?
An emergency tax code is what HMRC uses when your employer does not have enough information to apply your correct code. The most common emergency codes in 2026/27 are:
- 1257L W1 or 1257L M1 — the correct annual allowance (£12,570) but applied on a "non-cumulative" basis. Each month is assessed independently without reference to prior months.
- BR — all income taxed at 20% with no Personal Allowance. Common for second jobs or when your P45 has not arrived.
- 0T W1 or 0T M1 — no Personal Allowance at all, non-cumulative. The most aggressive emergency code.
Why does it happen?
The most common triggers are:
- Starting a new job without giving your employer a P45 from your previous role.
- Starting your first job and not having completed a Starter Checklist (formerly P46).
- HMRC not processing a tax code update in time for your first payday.
- Having multiple jobs simultaneously and HMRC not allocating allowances correctly.
- Returning to work from a break (maternity, sick leave, sabbatical) without updated records.
How much extra tax will I pay?
The impact depends on which emergency code you are on:
- 1257L M1 — you still get 1/12th of the Personal Allowance each month. The overpayment is usually small (tens of pounds per month) because you miss out on the cumulative catch-up but still get the basic allowance.
- BR — you lose the entire Personal Allowance. On a £3,000/month salary, you overpay approximately £209/month (£12,570 ÷ 12 × 20%).
- 0T M1 — worst case. You pay tax on everything with no allowance. Similar impact to BR for basic rate taxpayers.
What to do: step by step
Step 1: Give your employer your P45. If you left a previous job, you should have received a P45 within a few weeks. Hand it to your new payroll department. This gives them your tax code and year-to-date earnings.
Step 2: Complete a Starter Checklist. If you do not have a P45 (first job, lost P45, or gap in employment), ask your employer for a Starter Checklist. The statement you choose (A, B, or C) determines which code they apply. Statement A (first job since 6 April) gives the best result — your full Personal Allowance.
Step 3: Wait — or contact HMRC. Once your employer reports your new employment to HMRC (via RTI), HMRC will usually issue your correct tax code within 2–6 weeks. If it has been longer than 6 weeks, call HMRC on 0300 200 3300 or use your Personal Tax Account online to check and update your code.
Step 4: Check you get a refund. When HMRC issues your correct cumulative code, your employer will automatically refund any overpaid tax through your next payslip. You do not need to claim it separately. Check the "Tax Refund" or "Tax Adjustment" line on your next payslip.
Will I always get the money back?
Yes — if the overpayment happened in the current tax year, it is refunded through your payslip once the correct cumulative code is applied. If the tax year has ended (after 5 April) before you get the correct code, you can claim a refund directly from HMRC using form P50 or through your Personal Tax Account.
How to prevent it next time
- Keep your P45 safe when you leave a job and give it to your new employer on day one.
- If you do not have a P45, complete the Starter Checklist before your first payday.
- Register for HMRC's Personal Tax Account — you can check your code, update employer details, and spot issues early.
- If you have multiple jobs, keep track of how your Personal Allowance is allocated across them.
Check what your take-home should be
Use the income tax calculator with a custom tax code to see the difference between your emergency code and your correct code. Enter "BR" to simulate the emergency scenario, then switch to "1257L" to see what your pay should be. The difference is what you will be refunded.
For more on how tax codes work, see our tax codes explained guide.