Source: HMRC

HMRC has published specific detailed guidance on how it will calculate your profits to assess your entitlement to the Income Support Scheme Grant.

Full information is available here:

How HMRC works out total income and trading profits for the Self-employment Income Support Scheme
Find out how HMRC will work out your income and profits if you’re self-employed or a member of a partnership in the UK and have lost profits due to coronavirus (COVID-19).