Thanks for posting in the Community, leaveittoblondie.

The figures populated in the Prepare BAS screen is based from transactions recorded in QuickBooks coded with tax code. To adjust the BAS figures is we'll have to edit the amount of the transactions like your invoices or expenses.

You can run Transactions by tax Code report to see which transaction you can edit.

1. Click on the GST tab.
2. Click on Run reports.
3. Click on Transactions by Tax Code.
4. Select a report period and accounting method.
5. Click on Run report.
6. Select the transaction and edit it.

Drop by again in the Community if you have other questions.