The online service to claim the fourth grant will be available from late April 2021.
If you are eligible based on your tax returns, HMRC will contact you in mid-April to give you a date that you can make your claim from.
It will be given to you either by email, letter or within the online service.
HMRC look at your trading profits and non-trading income on your Self-Assessment tax returns to check if you meet the eligibility criteria for the fourth grant.
They also use your average trading profits to work out how much grant you will get.
You must make your claim on or before June 1, 2021.