Can you please confirm the tax setup version presently in use?
As Tax rate type was added in Version 82, as far as i remember in AX2012, the latest one around V64
I can tell the alternatives that I used to follow, I create multiple HSN and SAC for different rates like 84470001_5, 84470001_12, 84470001_18 to define different rates, and while showing in any report, we used to truncate the values after "_" symbol which gives proper HSN codes in print.
For Issue 2, are you looking for different rates due to changes in rates w.e.f 22-Sep-2025? As for sales return, if we use original tax rate, it takes from already linked sales invoice else calculate based on current setup.
In D365 you can write logic as you want or required, because it can be extended easily here.
We used to do some extension as well using RCS for tax configuration to be imported in AX2012, but not sure of current status.. as RCS was depreciated as well.
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Regards,
Neeraj Kumar
