Emergency Tax Codes Explained

Why new starters see emergency tax, what W1/M1 and 0T mean, and how refunds usually work.

Reviewed against official HMRC guidance

Tax year
2026/27
Last reviewed
August 2026
Reading time
7 min

What should I do if I am on an emergency tax code?

Who this guide is for: Aimed at people starting a new job whose first payslips look too high on Income Tax.

  1. Step 1New job / missing details
  2. Step 2Emergency tax code on payslip
  3. Step 3Provide P45 or starter checklist
  4. Step 4Cumulative code applied
Typical path — timing varies with HMRC and payroll.

Emergency tax is a temporary PAYE coding used when HMRC or payroll does not yet have enough information to operate your normal cumulative tax code. It can deduct more tax than you expect in the first pay periods of a new job.

  1. Check the tax code printed on your payslip.
  2. Provide a P45 to your new employer where available.
  3. Complete the starter checklist accurately.
  4. Check your HMRC Personal Tax Account for the issued code.
  5. Contact HMRC when the wrong code persists after a few payslips.

Why emergency codes arise

Common triggers include:

  • Starting a job without a P45
  • HMRC not yet issuing a full-year cumulative code
  • Payroll operating on a week-1 / month-1 basis until records update

Your employer may need your National Insurance number, start date and previous employment details. How PAYE works more broadly is covered in PAYE Explained.

W1, M1, X and cumulative versus non-cumulative

  • Cumulative codes look at pay and tax to date across the tax year and spread allowances accordingly.
  • W1 / M1 / X usually mean non-cumulative treatment — that week or month is taxed largely on its own, which can over-deduct if you have unused allowance earlier in the year.
  • 0T gives no Personal Allowance on that payroll.
  • BR taxes all taxable pay from that employment at the basic rate — not always an emergency label, but often seen in starter or second-job contexts.

For a fuller code table, see Tax Codes Explained.

Estimate take-home once your normal tax code applies Use the Income Tax Calculator

Frequently asked questions

What should I do if I am on an emergency tax code?

Check the code on your payslip, give your employer a P45 if you have one, complete the starter checklist accurately, review your HMRC Personal Tax Account, and contact HMRC if the wrong code persists after a few pay periods.

Will I get a refund?

Often yes, once the correct cumulative code is applied — either through later payslips or after HMRC reconciles your record. There is no fixed repayment timescale; check your Personal Tax Account.

Should I stop working until it is fixed?

No. Keep working and contact HMRC or your employer's payroll team with your National Insurance number and start date so the code can be updated.

Is emergency tax the same as a BR code?

Not always. BR taxes all income from that job at the basic rate without Personal Allowance. Emergency treatment can also appear as 0T or with W1/M1/X markers. See Tax Codes Explained for what each usually means.

Official sources

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This guide is for general information only. It is not tax, legal or financial advice. Always check the official guidance for your situation.