I got a corrected year 2020 1099-R for converting after-tax 401(K) to Roth IRA. Box 2(a) increased. I tried to amend the 2020 tax return in 2020 turbotax Premier (desktop version). But if I increase even $1 on box 2(a), I got more than $1000 federal and state tax. It makes no sense. Is this a bug of turbotax?
