The recommended approach would be to reverse the document and recreate it with the amendments.
To start, you may need to add the permission Cashbook: Reverse to your user account to have the ability to do this.
1. Navigate to the document. Select the ellipsis>Reverse.
 
2. Select the period you want to reverse into, though if you want to reverse into an earlier period you may need to unlock this. Enter the reason and then submit.
 
3. Once the document is reversed, select the dropdown and Copy exact.
 
4. Enter the date and the Period you would like to post this to (it will need to be an open period and preferably the same period as the reversal). Make the amendments to the line and Submit.
 
5. These two documents can then be matched off in the current bank reconciliation.


It is also worth considering a similar approach should a document with the incorrect VAT code applied is included in an already submitted VAT return.