Effective tax rate percentage derivation logic and workarounds during change periods

Summary / Question:

We try to understand how effective rate percentage is derived across all taxable transactions: AP, AR, External Taxable etc.
Looks like it is ALWAYS based on Transaction Date for ALL transactions. Is this correct?

If this is true, then please share your workarounds / thoughts on how you handle transition periods when tax % changes and you receive transactions for both periods. e.g. What if you receive correction invoice with old rate 2 or 6 months late? Or what if you receive rent invoice invoice in advance and you need to charge new rate for a future period and invoice date is still on the previous period… How you handle all this?