When coding data to be interfaced to Ledger Elite, you cannot override the default GST class. Although you are still able to alter the GST amount if you are using the Simplified Method for calculating your client's GST, Ledger Elite only accepts the GST class assigned to the chart code in Ledger Elite.
When BankLink data is exported and imported into Ledger Elite, it reads each coded transaction and if there are any overridden GST class to any Chart of Account code, it automatically reverts the GST code back to the default GST Class defined in Ledger Elite. This is a design feature in Ledger Elite.
To override the GST class for a Chart of Account code
There's 2 options for doing this:
Change the GST Class in Ledger Elite after BankLink data has been imported.
Create a new chart code or sub-account code in your Ledger Elite Chart of Accounts with the required GST class, refresh the chart in BankLink, and use the new chart code or sub-account code in the transaction you want to alter GST Class for.