Emergency tax code: W1, M1, X and NONCUM (UK 2026/27)
Emergency tax-code markers W1, M1, X and NONCUM explained: what they mean, where to check your code and what to do after a job change.
In one sentence
W1, M1, X and NONCUM are HMRC emergency tax-code markers which mean tax is calculated for the current pay period rather than cumulatively across the tax year.
Quick answer
- W1, M1, X and NONCUM are emergency tax-code markers
- They use the current week or month rather than cumulative year-to-date PAYE figures
- Give a new employer your P45, or complete the Starter Checklist where appropriate
- Use HMRC's tax-code checker and Check your Income Tax service to verify the record
- BR, D0, D1 and 0T have their own meanings and are not automatically emergency codes
Steps
- 1Check your latest payslip for the tax code printed near gross pay
- 2Look for W1, M1, X or NONCUM next to the number
- 3Give a new employer your P45 or a completed Starter Checklist where appropriate
- 4Check the income and employment details in HMRC's online services
- 5Contact HMRC if the details are not right and keep your PAYE documents
What is an emergency tax code?
GOV.UK identifies W1, M1, Xand NONCUM as emergency tax-code markers. They mean tax is calculated for the current pay period rather than cumulatively across the tax year. NONCUM may appear instead of a marker such as W1 or M1, depending on the payroll software.
You may see one after starting work where the employer does not have the information needed to operate the usual cumulative code. It is not a penalty, and it does not by itself prove that you have overpaid tax.
How do I spot it?
Check the tax code on your payslip. Examples include 1257L W1, 1257L M1, a code ending in X, or a code marked NONCUM. The number and letters before the marker still matter, so use HMRC's tax-code checker rather than relying on the marker alone.
What should I do after changing jobs?
- Give your new employer your P45 if you have one.
- If you do not have a P45, complete the HMRC Starter Checklist when it is appropriate to do so.
- Check your code and income details through HMRC's Check your Income Tax service.
- Keep your payslips and contact HMRC if the details shown are not right.
What is not necessarily an emergency code?
BR, D0, D1 and 0T are codes with their own HMRC meanings. They may be used for a second job, pension or other circumstances, but should not automatically be treated as emergency codes. For 0T specifically, see our 0T guide.
Where can I check the code?
Start with your payslip, then use HMRC's tax-code checker and your Personal Tax Account. If you have a single job or pension and no adjustment applies, the usual 2026/27 code is explained in our 1257L guide.
Need help with a tax question?
If your PAYE records interact with other income, benefits or Self Assessment, we can help you understand the wider position.
Book a call →Key terms
- Emergency tax code
- A code with the W1, M1, X or NONCUM marker. HMRC says those markers mean emergency tax-code treatment, where the current pay period is considered rather than the whole tax year to date.
- W1/M1 (Week 1 / Month 1)
- A non-cumulative PAYE basis where the current week or month is considered, rather than cumulative figures from earlier in the tax year.
- Cumulative tax code
- A PAYE basis that takes account of pay and tax earlier in the tax year.
- P45 / P46
- P45 is the document your previous employer issues when you leave a job. P46 was replaced by the Starter Checklist in 2013, the form a new employee fills in when they cannot provide a P45.
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