We were concerned that the extension to SEISS could leave more self-employed people without support than the initial scheme. HMRC based eligibility for the initial SEISS on tax return data up to 2018–19 and estimated, as part of initial planning at the start of lockdown, that this meant around 0.2 million newly self-employed people were unable to claim the grant. HM Treasury told us that it considered alternative arrangements, but that basing the grant awards on previously submitted data helped prevent the risk of people manipulating their returns to receive higher payments. HMRC confirmed that the extension to SEISS would continue to operate on the basis of 2018–19 returns despite HMRC accepting that the 2019–20 tax year ended in April 2020 and returns were starting to come in ahead of the 31 January 2021 deadline. The NAO noted in its report that the number of self -employed people excluded from the initial SEISS could have been greater than 0.2 million if lockdown occurred further from the annual tax return deadline. The SEISS extension occurred nine months after the 2018–19 deadline rather than the two months for the initial scheme. HMRC told us that if it had more up-to-date data on those who were the self-employed it may have been able to operate the scheme differently. Self- employed tax reporting on a quarterly basis to HMRC is due to come in as part of its Making Tax Digital project, but other than the pilot scheme, is not due until 2023.35