How can I prevent prior year changes to my accounts from affecting my current BAS?

Hello jennyganderton,

Let me provide some information about lodging BAS in QuickBooks Online (QBO). 

If a BAS period has been lodged in QBO that period is considered locked. Any changes made to the transactions within that period after lodging the BAS will show as an amendment in your next BAS period. Not only the changes will show as an amendment but will also affect your next BAS lodgement. Here's how to run a GST Amendment report:

1. Click on the GST tab.
2. Click on Run reports.
3. Click on GST Amendments.

To account the changes made to the relevant BAS period, and remove the amendment you can request your BAS to be unlocked. I'd recommend contacting our Customer Care Team in requesting the BAS to be unlodged. That way, we can ask for your details in a secure form.

Furthermore, you can turn on the close books feature in QBO in order to prevent changes in your past transactions. This is to ensure to keep your transactions the way it is. You can check this article to learn more about Close your books in QuickBooks Online.

Drop a comment below if you need more help. The Community is here to help you. Have a great day!