The W1 Tax Code Explained.
Everything you need to know about what W1 means for your payslip, your personal allowance, and your take-home pay in 2026/27.
Quick Definition
⚠️ Non-cumulative (Week 1) emergency basis. W1 is the weekly equivalent of M1. Each week's tax is calculated independently. The same advice applies — this is a temporary emergency basis and should resolve once HMRC has your full pay history.
How much tax will I pay on W1?
Use the interactive tool below to see how the W1 tax code impacts different salary levels. This calculation includes Income Tax and National Insurance for the 2026/27 tax year.
How W1 affects a £35,000 salary
Annual Income Tax
£6,996
20% of total income
Monthly Take-Home
£2,184
After Tax, NI & Pension
Based on 2026/27 tax rates.Full breakdown →
Is the W1 tax code right for me?
Tax codes are assigned by HMRC based on your reported income and circumstances. You might be on W1 if:
- This is your primary source of employment income.
- HMRC has recently updated your record following a change in benefits.
- You have started a new job and your previous P45 has been processed.
- HMRC believes you have underpaid tax in a previous period.
If you believe this code is incorrect, you should contact HMRC as soon as possible to avoid overpaying or underpaying tax.
Frequently asked questions about the W1 tax code
What does the W1 tax code mean?
W1 is the weekly equivalent of M1. Each week's tax is calculated independently. The same advice applies — this is a temporary emergency basis and should resolve once HMRC has your full pay history.
Is the W1 tax code correct for me?
Whether W1 is right depends on your personal circumstances. Typically, ⚠️ Non-cumulative (Week 1) emergency basis. If you have multiple jobs or benefits in kind, this might change.
How do I change my tax code?
You can change your tax code by contacting HMRC directly on 0300 200 3300 or by using the 'Check your Income Tax' service on the official gov.uk website.
Related Resources
Still not sure?
Try our full interactive checker to see every deduction on your payslip.
Quick reference — common UK tax codes
Last updated: July 2026. This information is for educational purposes only and does not constitute financial advice. Always verify your specific tax situation with HMRC or a qualified professional.