If a transaction has been locked into a finalised GST return, you can edit it as long as:
The amount of the transaction and coded lines remain the same
The GST content for each coded line also stays the same
If you need to change the overall amount of the transaction, the GST content, or add additional coded lines, have a look at How to create a reversal transaction.
How to correct a coded transaction
In the Actuals screen, go to the Completed tab.
Select the view you want to use to locate the item. Transactions displays the whole transaction while Coded lines displays each item by code.
Locate the transaction or coded line you want to edit.
TIP: Transactions and coded lines that have been included in a finalised GST return are indicated by the symbol to the left of the date.
Allocate the correct code, while ensuring the GST type and overall amount remain the same.
What if I have matched the transaction to an invoice?
If your transaction had been matched to a coded invoice, then you will need to change the coding within the invoice rather than in the transaction.