When using the flax tax provider and order discounts (not orderline), do the calculations try to account for removing the discount before taxes are applied?
As far as I can tell, it doesn't do this because it would mean distributing the order level discount across all of the lines. I haven't seen any hints that that occurs.
However, I wanted to confirm for sure before we try to find a workaround. There is a setting that was made available in 9.3.13 called "Apply discount before taxes". However I wasn't able to find out how this impacts the calculations, and I couldn't reproduce a way to see it change the calculation for either order or orderline discounts.
Note that Avalara does handle this. What it does is to distribute the order discount across all of the lines so that the tax per line is reduced. So logically it's possible to do this with the flat tax provider, although I'm sure it's not trivial.
Thanks,
Scott