When does a Roth conversion actually make sense?
The sweet spot is usually the gap between when you retire and when RMDs and Social Security kick in — often ages 60 to 72. Income is lower in those years, so the tax rate on a conversion is as cheap as it's going to get.
What is the fill-the-bracket strategy?
Instead of converting everything at once, you convert just enough to fill your current tax bracket without spilling into the next one. If you're in the 12% bracket with room to spare before hitting 22%, you convert up to that line each year.
Does a Roth conversion affect Social Security taxes?
Yes. The converted amount adds to your combined income, which determines how much of your Social Security benefit gets taxed. A large conversion in the wrong year can flip your SS from 50% taxable to 85% taxable.
Roth conversions are permanent since 2018 — you can no longer undo one after the fact. Run the numbers before you convert, not after.
See how a conversion affects your Social Security taxes using our Social Security tax calculator.