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What is a CWF1 Form?

What is a CWF1 Form?

The CWF1 form is used to register or re-register with HMRC as a sole trader. You can also register as a sole trader online.

When should I submit my CWF1 form?

If you need to tell HMRC you’re self-employed using a CWF1 Form, the deadline is 5th October in your second tax year. Make sure you register in enough time to submit your Self Assessment tax return to minimise the risk of receiving a penalty for late registration.

For example

If you start your business in November 2025:
  • Your first tax year is 2025/26
  • Your second tax year runs 2026/27
The deadline to register using this example is 5th October 2026.

What’s the difference between a CWF1 Form and a SA1 Form?

Submitting a SA1 Form signs you up for Self Assessment, but there are lots of different reasons why you might need to register. A CWF1 Form confirms to HMRC you’re setting up your own business.

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What do I need to include on a CWF1 form?

The form will ask you for your personal details, National Insurance number, and the nature of your self-employed business. This includes the business name you plan to trade under, and the address where the business will operate.

What happens after I submit a CWF1 form?

HMRC will issue you with a Unique Taxpayer Reference (UTR) number, which you’ll need each time you submit a tax return.

As a self-employed person you’ll need to maintain good bookkeeping records which show how much money your business earns and what it spends. This information will help you complete your tax returns more easily, and make sure you claim tax relief for any allowable expenses!

Learn more about our online accounting services for businesses. Call 020 3355 4047 to chat to the team, and get an instant online quote.

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