Last updated on:
March 17, 2024

If you're embarking on a journey as a self-employed individual in the UK, familiarizing yourself with the CWF1 form is crucial. This form serves as your official notification to HMRC (Her Majesty's Revenue and Customs) that you've started earning as a sole trader and need to complete a Self Assessment tax return.

What is Self Assessment?

Self Assessment is a system used by HMRC to collect income tax from individuals who earn money outside the traditional PAYE (Pay As You Earn) system. This includes the self-employed, who receive their income gross, without tax automatically deducted. It's the self-employed individual's responsibility to report their earnings and pay the correct amount of tax annually.

Key Dates for Self Assessment

The tax year in the UK runs from 6th April to 5th April the following year. For those starting to trade in September 2022 (during the 2022/23 tax year), the deadline to pay the first tax bill is by 31st January 2024. This allows ample time post the tax year's end to calculate earnings, expenses, and submit the tax return.

Completing a CWF1 Form

The CWF1 form requires you to provide:

  • Personal details (name, address)
  • Business address (if different)
  • National Insurance number
  • Detailed business information

This form can either be completed online or submitted on paper, catering to personal preference. The completion of this form is a critical step in formally registering as self-employed and ensuring compliance with tax obligations.

Fill in your CWF1 form with HMRC.

The Registration Process

Upon submission of the CWF1 form, HMRC will issue a Unique Taxpayer Reference (UTR) number. This UTR is essential for filing your Self Assessment tax returns and for any communication with HMRC regarding your tax affairs.

Registration Deadline

Regardless of whether you opt for paper or online registration, the deadline to register for Self Assessment is 5th October in the year following your trading start date. It's vital to adhere to this deadline to avoid any penalties and ensure your tax affairs are in order.


Navigating the transition to self-employment involves understanding and fulfilling your tax obligations. Completing the CWF1 form is a foundational step in this process, ensuring you're registered with HMRC and ready to manage your tax responsibilities effectively. Remember, staying ahead of deadlines and maintaining accurate records will streamline your Self Assessment process and keep tax-related stress at bay.

By clicking “Accept”, you agree to the storing of cookies on your device to enhance site navigation, analyse site usage, and assist in our marketing efforts. View our Privacy Policy for more information.

Arrange your free initial consultation today.

Book Free Consultation
UK's best rated accountant 2021
Rated Excellent
5 Stars
on Trustpilot