I am a big fan of TaxCalc but they don't see us Mac users as an important market (still no network version for us ....)
Today I installed Big Sur and TaxCalc does not work. Despite there being Beta versions for some months, the TaxCalc Helpine say that they heard about it from customers!
I put it to them that if all Windows users lost the program overnight, they would be in the doo doo big time.
Luckily I have another Mac so am screen sharing with it - and will be keeping my fingers crossed that the problem will be fixed soon
NOT GOOD ENOUGH GUYS !!