HMRC are advising customers to check the pre-populated SEISS entry on their Income Tax Self-Assessment Return and where necessary, delete the pre-populated figure and manually enter the correct amount, a spokesperson advised “our system will not process a return if the SEISS grant entry does not match our record of the amount paid.”

AccountingWeb reported that they’ve had several reports about a bug in HMRC’s Self-Assessment application programming interface (API) that is corrupting figures entered on 2020-21 returns for SEISS grants.

The first report arrived from an AccountingWEB member, who reported that a claim for £1,000,000 had appeared on one of their clients’ tax returns! With other reports confirming this was not an isolated incident.

The HMRC spokesperson continued: “we are aware of a problem with the way that SEISS grants received in the 2020/21 tax year are being presented on the individual income API. Figures are being presented in pence rather than pounds. This is impacting individuals who use commercial software only.

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