Business asset disposal relief (BADR) reduces the rate of capital gains tax for gains made from the sale or transfer of a business, assets of that business and sometimes part of a business. The rules are widely drawn, but before these are considered some basic conditions must be met.
The Flow Chart - Business Asset Disposal Relief will help you decide if you are entitled to claim.
Definitions for the flow chart:
HMRC provides a comprehensive helpsheet at https://www.gov.uk/government/publications/entrepreneurs-relief-hs275-self-assessment-helpsheet
Where you establish that you are entitled to BADR our Business Asset Disposal Relief Checklist and Rent or Business Asset Disposal Relief Checklist may help you with quantifying and making your claim.