SolvedVAEC7820 | Error correction for VAT returns: Processing: Initial check for return adjustment
From HM Revenue & Customs · VAT Assessments and Error Correction
When an officer receives a separate notification of an under-declaration of VAT that is below £10,000, and the due date for the return for the period in which they discover the error has not yet passed, they should contact the person to confirm that they do not want to wait until the end of the return period and include the adjustment in their return.
This is to ensure that the person is aware that there is no liability to interest when an adjustment is made in the VAT return for the period of discovery.