I have been doing Roth conversions since 2008, the taxable conversion amounts total $320k and the incremental impact on taxes has been close to $38k. I will be 70 next year and the Roth accounts will have grown to about $600k. If these assets had remained in my tIRA, then they would be hit with RMDs and over the next 15 years (assuming 6% growth) there would be $531k in taxed RMDs plus $682k of assets remaining that would also be taxed beyond age 85. Total 1.2M taxable at whatever rates in affect and I would have been paying taxes on a lot of money I most likely wouldn't need to have withdrawn.