You did exactly what I would have done, I.E. run the numbers through on the 2020 software and see what happens... there are not too many tax preparers I would venture to say that are experts on the AMT.... but as you know the 2021 tax law can change at any time even in 2022 and made retroactive.... also as you said it is usually a good idea to spread income over a period of years instead of taking a lump-sum in one year ..... Just my opinion...