Roth Conversion

A Roth conversion is a voluntary tax-accelerating move: you deliberately pay ordinary income tax on some or all of a traditional IRA/401(k) balance today, in exchange for moving that money into a Roth account where it compounds and is distributed tax-free. For the right household at the right time, it is one of the highest-return moves available in retirement planning.

The decision is primarily an interest-rate-vs-inflation bet on your future tax bracket. If you expect to be in a higher tax bracket later (because of RMDs, Social Security timing, a surviving-spouse filing change, or because you expect tax rates in general to rise), converting now at today's known rate beats paying tomorrow's unknown rate later.

The sweet spot for Roth conversions is usually the years between retirement (when earned income stops) and the start of Social Security or required minimum distributions. During that window, taxable income is often much lower than it will be for the rest of your life — meaning you can 'fill up' the lower tax brackets with converted dollars at the lowest effective rate you'll ever see again.

Conversions are fully taxable in the year they happen. There is no 'recharacterization' (undo) option since the 2017 Tax Cuts and Jobs Act — once you convert, it's permanent. That means sizing the conversion correctly, relative to your other income that year, is critical.

Large conversions can also trigger secondary tax effects: higher IRMAA premium on Medicare Parts B and D, more of your Social Security becoming taxable, and occasionally exposure to net investment income tax. A good planner models all of these before executing a conversion.