Hello, @T Yosh. I appreciate your prompt response and follow-up on this. Let me share additional information regarding sales tax in QuickBooks Online (QBO).
For now, we don't have any information yet about QuickBooks will change the rate automatically from 8% to 9% in January 2024.
Regarding your question about how changing the rate affects transactions, there's really a possibility that your prior transactions will be affected if you edit the tax rates. This could also affect your sales tax tracking. That said, it would be okay for you to create a custom rate rather than updating or editing an existing one. Using the default codes is not mandatory and it's all up to you if you use it or not.
I've added these articles to learn more about GST tax codes:
The Community team is always around if you have further clarifications and QuickBooks concerns. Have a good one.
