The Roth conversion decision in plain English

Roth conversions can save a household six figures, or cost you money. Here is when they make sense, and when they don't.
A Roth conversion moves money from a pre-tax IRA into a Roth IRA. You pay taxes today so that you (and eventually your heirs) never pay taxes on that money again.
Conversions tend to make sense when current tax brackets are lower than your expected future brackets, when you have cash outside the IRA to pay the tax, and when you have heirs who would otherwise inherit pre-tax money under the 10-year rule.
They tend to backfire when they push you into a higher Medicare IRMAA bracket, when they raise your Social Security taxation, or when you'd have to use IRA dollars themselves to pay the tax.
We model conversions year by year, not as a one-time decision. The window between retirement and age 73 is often the most valuable conversion window of a client's life.