Money

UK Emergency Tax Code Explained: Why You Are Taxed Too Much on a New Job

2 min read

In this guide
  1. What is a tax code?
  2. How do you find your tax code?
  3. What do the emergency codes look like?
  4. When does it apply?
  5. What if you paid too much tax?
  6. Common mistakes
  7. FAQ
    1. Is it my responsibility to check my tax?
  8. Key takeaways
  9. Related guides
  10. Sources

Quick answer: An emergency tax code is a tax code that ends in W1, M1 or X, or shows NONCUM on your payslip, depending on your employer’s payroll software. It means tax is worked out only on what you are paid in that week or month, so you could pay the wrong amount. If you paid too much, you can get a refund.

What is a tax code?

Your tax code is used by your employer or pension provider to work out how much Income Tax to take from your pay or pension. HMRC tells them which code to use, and you get a separate code for each employment or pension.

How do you find your tax code?

  • Check your current-year code online (you need to sign in or create an online account).
  • Use the HMRC app.
  • Look on your payslip.
  • Check a Tax Code Notice letter from HMRC, if you received one.

What do the emergency codes look like?

Ending Meaning (GOV.UK) Example
W1 Paid weekly 1257L W1
M1 Paid monthly S875L M1
X Pay dates vary C663L X
NONCUM May appear instead, depending on payroll software –

When does it apply?

  • When you start a new job and your employer does not have your previous income and tax details. This is usually temporary, and giving them your P45 can help remove it.
  • When you start company benefits or the State Pension. It lasts until the end of the tax year, then you move to a non-emergency code.

What if you paid too much tax?

You can get a tax refund. GOV.UK has a separate guide, “If you’ve paid too much or too little tax”.

Common mistakes

  • Ignoring a W1 or M1 code for months.
  • Not giving your employer your P45 when you have one.

FAQ

Is it my responsibility to check my tax?

Yes. GOV.UK says it is your responsibility to make sure you are paying the right amount of tax.

Key takeaways

  • W1, M1, X or NONCUM signal an emergency code.
  • It is usually temporary at a new job.
  • Check your payslip and ask for a refund if you overpaid.

Last updated: October 2026. This is general information, not tax advice.

Sources

  • GOV.UK: Tax codes
  • GOV.UK: Emergency tax codes

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