The government have updated literature about the measure put in place for self-employed and employees.

EMPLOYERS
For business looking to claim wages for staff through the Coronavirus Job Retention Scheme please read this
https://www.gov.uk/guidance/claim-for-wage-costs-through-the-coronavirus-job-retention-scheme
Please note that Director of their own company who pay themselves a salary and dividends through the own company are not covered by the self-employed scheme.
If you are genuinely having to furlough yourself, you will be entitled to 80% of your salary (not dividends).
To be furloughed you genuinely cannot be doing any work for your business, so please consider this carefully.

SELF EMPLOYED
To find out more details about the self-employment scheme please read here
https://www.gov.uk/guidance/claim-a-grant-through-the-coronavirus-covid-19-self-employment-income-support-scheme
Please pay attention to some of the detail which wasn’t previously known – i.e. £50,000 profit cap and also note the other potential ways the government can help at the bottom.

Once again, we can only interpret what is within those links, as can you. We feel that they are pretty black and white, and it is also clear that details on how one would physically make a claim will become clear in due course.

HMRC have made it clear you do not at this stage have to contact them, as they are aware of those that are UK registered taxpayers and will be in contact in due course
With regards to those that do not have three years on record, I believe the intention is to use what is on record. They have not made clear whether they would accept a 2019/2020 filing though for those without three years on record or have just become self-employed. They may expect people to use the Universal Credit scheme – https://www.gov.uk/universal-credit
Once again – kind regards and stay safe!