Issue: Stock taxation by date/ history

Hello. I’ve been referred here from github to get more people to discuss this feature i’m proposing.
Essentially what i am saying is we should have a way to better manage taxation on a stock item. there should be a “history” or management option where one could set taxation by rules, maybe by date or any other rule.
The reason for this request is that in india, just some weeks ago, the government decided to change taxation on multiple items and gave an implementation date to go with it. In this case, it was 27 july.
what this meant was, an item which was previously in say 28% tax bracket would now be in 18% or even 12%. the point is we were given a date from which these new tax rates would be implemented.
the current setup has a problem because lets say an item “A” is in 18% and tomorrow i set it to the new rate, 5%. Thats fine but what if had purchased that item in the earlier tax rate and it got delivered in the new tax rate. i am aware of the immutable ledger and stuff but this is an issue. so now i would then have to go back to the item, change the tax rate to old one, make the purchase entry and then turn it back.
sounds like a lot unless i had a “implement by date” which meant doing any entry in the pre implementation date would be taxed in the old rate and vice versa.
Hope i made some sense and i’m willing to discuss it further