HMRC has finally produced some guidance on how to report the first three SEISS grants on SA tax returns for 2020/21. But this guidance only directs you to the notes to the SA returns, so you need to dig through several documents to find all the answers you need.
The SEISS grants are reported for the tax year in which they are received, and must be included in these boxes on the various different SA returns:Except in the rare case where a partnership received the SEISS grants directly rather than the partners, the SEISS grants should be excluded from the turnover of the business.
The taxpayer must report the total amount of SEISS grants received in the tax year, less any amounts which have been repaid to HMRC.
Some tax software pre-populates the tax return with the amounts of SEISS grant paid to the taxpayer. These figures are apparently provided automatically by the SEISS API which connects the tax software to HMRC’s systems.
If your tax software claims to pre-populated the tax return with the SEISS totals, you need to treat those figures with utmost caution. Many SEISS amounts have been out be a factor of 100, and in some cases the SEISS grant is reported as zero when the taxpayer has in fact received some grant.
It may be easier to ask your client directly for proof of the SEISS grants they received during the tax year.