It comes as details of the extended furlough scheme were also outlined.
How the scheme works
Until now, self-employed workers who qualify have been in line for a grant of 80% of their average profits, up to £2,500 a month for three months. This is being paid in one instalment.
Some 2.3 million of these workers have signed up for grants totalling £6.8bn.
Those whose work has been affected by coronavirus will still be able to apply for this lump sum until 13 July.