A Roth conversion is a simple trade: you move money from a pre-tax retirement account into a Roth, pay income tax on the amount now, and in exchange that money — and everything it earns — is never taxed again. Whether that trade wins depends entirely on one question: is your tax rate today lower than the rate you'd otherwise pay later?
For many people, there's a specific stretch of life when the answer is clearly yes — and it has a start date and an end date.
The window
Say you retire in your early sixties. The paycheck stops, so your taxable income drops — sometimes dramatically. But required minimum distributions from your pre-tax accounts don't begin until your seventies. In between sits a run of years where your tax brackets are, in a sense, sitting empty.
Those years are the window. Converting during them means filling today's low brackets deliberately — paying tax at rates you chose — instead of waiting for RMDs to force income on you later at rates you didn't. Done across several years, conversions can shrink future RMDs, reduce lifetime taxes, and leave heirs an account that arrives tax-free.
RMDs are the IRS's schedule. The window is yours.
The quiet reason the window matters: the survivor's tax
Married couples file jointly, with wide brackets. When one spouse passes, the survivor typically keeps most of the income — and files single, in brackets roughly half as wide. The same income, taxed noticeably harder, for the rest of the survivor's life. Conversions done while filing jointly are one of the few planning tools that directly soften that outcome.
What can go wrong
Conversions are permanent, and enthusiasm is not a strategy. The common mistakes:
- Converting too much in one year. A large conversion can spill into higher brackets and defeat the purpose. The bracket you fill matters more than the total you convert.
- Tripping Medicare surcharges. Conversion income counts toward the thresholds that set Medicare premiums two years later. Crossing one by a dollar raises premiums for a full year.
- Paying the tax from the IRA itself. Every dollar withheld for taxes is a dollar that never gets to grow tax-free. The math works far better when the tax is paid from outside funds.
- Ignoring everything else in the year. Capital gains, a house sale, a big charitable gift, a final bonus — conversions share the return with all of it. The right amount is a whole-picture number, not an account-level one.
This is a math problem, not an opinion
Whether to convert, how much, and in which years is answerable — with a year-by-year model of your income, spending, brackets, and account mix, updated as the law and your life change. That model is the heart of the retirement plans we build, and because our tax planning is CPA-led, the conversion decision and the tax return it lands on are made at the same table.
If you're within ten years of retirement — on either side — it's worth finding out whether your window exists, how wide it is, and what it's worth. Some of the most valuable planning years of a lifetime are the quiet ones nobody calls about.
Educational only — not investment, tax, or legal advice. Every situation is different; the right answer depends on the numbers, and that's what the strategy session is for. Investing involves risk, including possible loss of principal.