Between your last paycheck and the arrival of required minimum distributions sits a finite stretch of low-bracket years. Roth conversion planning is the discipline of using that corridor deliberately instead of letting it expire unused.
The year you stop working, your ordinary income often falls sharply. If you delay Social Security and live on taxable assets for a few years, your reported income can drop into brackets you have not seen since early in your career. Then, at RMD age, the government forces distributions from your traditional IRA and 401(k) whether you need the money or not, and Social Security stacks on top. Income, and your bracket, jumps back up.
The corridor is the span between those two events. During it, you can move dollars from tax-deferred accounts into Roth accounts on purpose, paying tax at today's temporarily low rate so those dollars, and every year of growth after them, are never taxed again.
Not from carelessness. From defaults. Advisers who are paid to manage portfolios rarely volunteer to shrink the taxable account that pays the conversion tax. CPAs see the corridor in April, one year at a time, after the year is already closed. And the household itself is enjoying the first low-tax years in decades, so writing a voluntary check to the IRS feels unnatural.
The result is predictable: several years at the bottom of the bracket schedule pass unused, and then RMDs arrive to tax the entire deferred balance at rates nobody chose. A corridor is only valuable if someone models it, sizes it, and executes it every year it is open.
Converting is not automatically smart. It is a trade: a known tax bill today against an estimated tax bill avoided later. Four variables decide whether the trade is worth making, and in what size.
The core spread. Converting at 24% to avoid a projected 32% later is a fundamentally different decision than the reverse.
Medicare premium surcharges are cliff-based. One dollar of excess conversion income can raise two years of premiums, so conversion sizing must respect the thresholds.
Inherited traditional IRAs must generally be emptied within ten years, often during the heirs' peak earning years. If your children out-earn you, the relevant future rate may be theirs, not yours.
Converting before leaving a high-tax state, or after arriving in a no-tax state, can swing the math materially. Residency timing belongs in the model.
A directional illustration of the trade, using your own assumptions for rates and conversion size. It is deliberately simple: real corridor design layers in bracket edges, IRMAA thresholds, state tax, and heir analysis. Use it to see the shape of the decision, then model it properly.
Assumptions: conversions begin at retirement age (or current age if later) and occur once per year for the years selected, capped at the starting balance. Each converted amount is compounded at a flat, illustrative 5% annual growth rate from its conversion year to age 75, the assumed RMD start age. Future tax avoided equals that grown value multiplied by your assumed later marginal rate; tax paid equals each conversion multiplied by your assumed current marginal rate. The break-even figure is the future marginal rate at which the trade would be a wash. This is a directional educational illustration, not tax advice or a projection of your outcome. It ignores bracket edges, IRMAA surcharges, state tax, NIIT interactions, growth on the tax dollars themselves, and the account that pays the conversion tax. Model your actual situation with your adviser and tax professional.
Ideally from taxable accounts, not from the converted amount itself. Paying the tax from outside the IRA keeps the full conversion working tax-free, which is a meaningful part of the estimated benefit. If the tax can only be paid by withholding from the conversion, the math weakens and, before age 59½, can trigger penalties. This is one reason corridor planning starts with the taxable account, not the IRA.
No. Recharacterization of conversions was eliminated by the 2017 tax law, so every conversion is permanent once executed. That is precisely why we size conversions against bracket edges and IRMAA thresholds before year-end rather than converting a round number and hoping. Irreversibility raises the standard of care; it does not argue against converting.
Often not for those dollars. Charities pay no income tax, so traditional IRA assets destined for charity are already effectively tax-free at death, and qualified charitable distributions can satisfy RMDs directly. The sharper design usually earmarks pre-tax dollars for charity and converts the dollars intended for family. Intent drives the account-by-account answer, which is why conversion planning and estate planning are one conversation at Wealthstone.
Every low-bracket year that passes unmodeled is capacity you do not get back.
