This relates to adjustments such as our opening balance journal adjustments, the following rule applies.
Where the input tax claim or output tax due on a supply has been changed as a result of an adjustment, you do not need to amend the digital record of the supply. I.e. you do not need to go back and amend the original transaction.
It mentions in the VAT notice that journals can therefore be manual adjustments i.e. entered as a T9 transaction (Sage)/ No VAT transaction (Xero).
Other examples of this include the partial exemption calculation, which again can be adjusted manually.
The drug rebate manual adjustment can also continue as before, when using Sage, if this is something that you currently do.