You can register online through the VAT registration service on GOV.UK, using a Government Gateway account or by authorising an accountant or tax agent to apply for you. You will generally need your business details, National Insurance number or Unique Taxpayer Reference, bank details, turnover information and details of your accounting periods. Registration is usually compulsory if your VAT-taxable turnover exceeds the current threshold in a rolling 12-month period, although businesses can register voluntarily. HMRC will confirm your effective registration date and VAT number, so check the official GOV.UK guidance for the latest threshold and requirements.