Guides › Public Services › Emergency Tax Code: Why You Have One and How to Fix It
Emergency Tax Code: Why You Have One and How to Fix It
An emergency tax code ends in W1, M1 or X, for example 1257L W1. You usually get one when you start a new job and your employer does not have your previous pay details, or when you start company benefits or the State Pension. It works out tax only on that period's pay. Give your employer your P45 or fill in the starter checklist. HMRC usually updates the code within 35 days, and you can claim back any tax you overpaid.
At A Glance
Your Rights
What the rules say, with a link to the official source for each.
Emergency Tax Codes
What They Look Like
The code ends in W1 (weekly pay), M1 (monthly pay) or X, for example 1257L W1. Your payslip may show NONCUM. Tax is worked out only on that week's or month's pay. source
Why You Have One
Usually a new job where your employer does not have your previous income and tax details, or starting company benefits or the State Pension. source
Fixing It
Give your new employer your P45, or ask your old employer for it. If you do not have one, fill in the starter checklist. HMRC usually updates your code within 35 days of starting; if it is still wrong after that, update it. source
Getting Money Back
If you paid too much tax you can claim a refund. If you paid too little, you stay on the emergency code until the right tax is paid. source
Time Limits to Know
Miss a deadline and you can lose a right. Check the dates on your own paperwork.
- 35 daysHMRC usually updates your codeAfter you start
Steps to Take
Step 1 of 5
Check the code on your payslip.
Step 2 of 5
Give your employer your P45 or starter checklist.
Step 3 of 5
Check your code in your personal tax account.
Step 4 of 5
Update it if still wrong after 35 days.
Step 5 of 5
Claim back any overpaid tax.
(Tap the numbers to reveal steps)
Where to Go If It Is Not Put Right
Your options, in order, and when each one applies.
Your Personal Tax Account
Sign in on GOV.UK to check your tax code, income and letters.
HMRC
Contact HMRC through your personal tax account, the HMRC app or the phone and post details on GOV.UK.
Good to Know
Small things that make your complaint stronger.
Your personal tax account shows your current code and the income HMRC is using.
Scotland has its own Income Tax rates and bands. The rules on returns, penalties and HMRC complaints apply across the UK.
Want Help?
If you would like one of our team to look at your problem, our initial case review is free. We cannot guarantee any outcome and we do not give legal advice.
Lead reviewer
Luke Marley
Founder and Lead Reviewer
Luke founded CPUK in 2026 after seeing how hard it is for ordinary people to get problems with companies put right. He oversees our guides and checks them against official sources.
Research by Katie Burt, Co-founder and Operations Lead (17 years in the care sector, including managing services for vulnerable adults), and the CPUK Research Team. Researched with AI-assisted research tools, then checked and corrected by our team.
Last checked: 15 October 2026. We are not paid by the companies we write about. Adverts never affect our guidance. Read our editorial policy.
Sources and official links
- gov.uk/tax-codes/emergency-tax-codes Checked 15 October 2026