HMRC yesterday issue guidance on claiming the fifth SEISS grant. Full details can be found at the link below.
The fifth grant will be determined by a turnover test. The test considers how much your turnover has gone down by in the 2020-21 tax year due to the pandemic.
The article below at accounting web has some interesting comments about the turnover test, you will need to register at accounting web when viewing to see the details;
Taxpayers who were not eligible for the fourth grant, will not be eligible for the fifth grant either as HMRC are using the same tax returns to determine eligibility for both grants, see link below;
A reminder also that SEISS grants are taxable and subject to self-employed National Insurance contributions and need to be reported as part of the Self Employment income in the tax year they are received.