SALF1300 - Self Assessment: the legal framework: Correction of digital records and quarterly updates
If a relevant person keeps a digital record or gives HMRC a quarterly update and discovers an error or omission in that record or quarterly update, they must use functional compatible software to correct the error or omission as soon as possible.
Corrections must be submitted by the day on which the next quarterly update is required. There is no requirement to resubmit an earlier update.
Where the error relates to the fourth quarterly update or the quarterly update period in which the digital termination date falls, the correction must be submitted to HMRC no later than the filing date for the return for that digital obligation tax year.
Where the error is identified after the tax return is submitted, an amendment to the return may be made within time limits.