Thanks to everyone for the great answers. We are converting at the $250k+ level to reduce the balance in our IRA's (for at least 10 yrs), the combined effective Fed/State tax rate is ~21% (yes some income is in the 24% bracket) and have factored in the IRMAA penalties . This is needed to reduce the RMD's, which when combined with SS (not taking until 70) would have put us at least in the 32-35% Fed with (with annual growth of 6-7%, but invested very aggressively so likely a higher growth rate) and if the TCJA expires at the end of 2025, 33-35%, plus ~6% state. So will keep my eye out in Q1 for a sharp market downturn for a large conversion, then pay the estimated taxes quarterly. This was very helpful and am sure it will be for others who are contemplating Roth conversions.
