To trade as a sole trader and work as self-employed, you will be required to register as self-employed with Inland Revenue within 3 months of starting to trade. Failure to do so could result in a penalty of £100. You can do this by completing a form CWF1 or calling your local Inland Revenue office.
As a sole trader/self employed person or company director you will be required to complete a self-assessment and pay tax once a year.
You will also be required to make weekly Class 2 NI contributions of £2.05 per week. If you earn over £4745 during a tax year, you will also become liable for Class 4 NI.