What is a CWF1 Form and How to Get It: A Guide for Self-Employed Individuals

cwf1 form

If you’re starting your own business or working as a freelancer in the UK, you’ll need to understand a key tax document: the CWF1 form. This form is essential for registering your self-employed status with Her Majesty’s Revenue and Customs (HMRC).

What Exactly is the CWF1?

The CWF1 (Construction Workers Form 1) is the official form used to register with HMRC as a self-employed individual (sometimes called a sole trader). By submitting this form, you’re essentially informing HMRC that you’re responsible for paying your own taxes and National Insurance contributions.


cwf1 form example

Why Do You Need It?

  • Tax Reporting: The CWF1 initiates the process of creating your Self Assessment tax return record.
  • National Insurance: Registering for self-employment triggers your Class 2 National Insurance obligations.
  • Compliance: It’s your legal obligation to notify HMRC when you begin working for yourself.

How to Get a CWF1 Form

There are a few ways to get your hands on a CWF1:

  1. Online: The most convenient method is to register for self-employment online through HMRC’s website. This includes filling out the digital version of the CWF1.  You can find the online registration at: https://www.gov.uk/register-for-self-assessment.
  2. Paper Form: You can download a printable CWF1 form from HMRC’s website, fill it out and send it by post. This form can be found on the GOV.UK website.
  3. Telephone: You can call HMRC and request them to take your information and register you over the phone.

Key Information to Include on Your CWF1

  • Personal details (name, address, date of birth)
  • National Insurance number
  • The date you started working for yourself
  • The nature of your business
  • Business address (if different from your home address)

Important: The CWF1 Deadline

You need to submit your CWF1 by October 5th following the end of the tax year in which you started your self-employment. For example, if you became self-employed in February 2023, the tax year ends in April 2024, so your CWF1 would need to be submitted by 5th October, 2024.

Your UTR Number

Once you register using the CWF1, HMRC will issue you a Unique Taxpayer Reference (UTR) number. This 10-digit number acts as your personal tax identifier. You’ll need this UTR to file your Self-assessment tax returns and interact with HMRC regarding your taxes.

The SA302 Form

Once HMRC processes your CWF1, they will send you a self-assessment tax return pack. A key part of this is the SA302 form, which details how much tax and National Insurance you owe for that tax year. It’s essential to keep track of your income and expenses to complete the SA302 form and file your Self Assessment tax return on time.

Key Takeaways

  • The CWF1 is a non-negotiable form for self-employed individuals in the UK.
  • Submitting the CWF1 is the first step in your Self Assessment journey.
  • You can register online, by post, or over the phone.
  • Don’t miss the deadlines — late submissions can result in penalties.

Additional Tips

  • Keep thorough records of your business income and expenses for tax calculation purposes.
  • If you’re unsure about any aspect of self-employment taxes, seek professional advice from an accountant or tax advisor.

By understanding the CWF1 form and its importance, you’ll be well on your way to managing your self-employment tax obligations in an efficient and compliant manner.


Navigating tax forms and requirements as a self-employed individual can be tricky.  While you can handle these tasks yourself, consider the benefits of working with experienced accountants. Accountants like those at TaxAce LTD specialise in self-employed taxes, ensuring you stay compliant, maximise deductions, and can focus on growing your business.

Contabila UK - Founder and CEO -TaxAce - Iurie Bivol

Iurie Bivol


Entrepreneur and accountant with 15 years of experience in the UK.

Contabilitate UK - Senior Tax Assistant - Alina Costreie

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