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Roth conversion ladder calculator

Between the year you stop working and the year Social Security starts, your taxable income is usually the lowest it will ever be. This sizes a multi-year ladder that fills the bracket you choose, and shows what is still sitting in the traditional account when required distributions begin at 73.

Converted over 12 gap years
$1,135,655
at a cost of $107,079 in federal tax, an effective 9.4% on the amount moved
Room inside the 12% bracket$121,000/yr
Pre-tax balance at RMD age with the ladder$0
Pre-tax balance at RMD age without it$2,156,902
First RMD at 73, with the ladder$0
First RMD at 73, without it$81,393
The ladder reduces your first required distribution by about $81,393, and every one after it.
Conversions at 63 or later set the income Medicare uses at 65. Check IRMAA thresholds before converting in those years.

Why the gap years are the whole opportunity

For most of a working life there is no room in the lower brackets, because salary already fills them. After required distributions begin at 73, there is no room either, because the distributions fill them whether you want the income or not. In between sits a window where earned income has stopped and forced income has not started, and that window is the only time most people can move money at a rate they choose.

A ladder uses that window deliberately: convert enough each year to reach the top of a chosen bracket and no further, repeat until the window closes. Every dollar moved is a dollar that will not be taxed again, will not be forced out at 73, and will not raise the taxable portion of Social Security later.

The trap at the end of the window

Medicare sets premiums from income two years prior, so conversions made at 63 and 64 land on the premiums you pay at 65 and 66. Those thresholds are cliffs rather than slopes: one dollar over raises the premium for the entire year. It is the most common way a well-intentioned ladder costs more than it saves, and the reason starting early matters as much as sizing correctly. The IRMAA calculator shows where the lines sit.

What this calculator simplifies

Federal ordinary brackets only, at 2026 figures, with the standard deduction. It does not model state tax, capital gains stacking, the taxable portion of Social Security, ACA premium subsidies during the same years, or the survivor's move to single-filer brackets. Each of those can change the right answer, and the last two often change it the most.

For a single year rather than a ladder, use the Roth conversion calculator. If you are retiring before 65, conversions also raise the income that sets your ACA subsidy, which is a direct tradeoff worth seeing together rather than separately; the health insurance gap before Medicare covers that collision, and the planbend app models both at once against your own numbers.

Common questions

What is a Roth conversion ladder?
A series of partial conversions from traditional retirement accounts to Roth, done over several years rather than all at once, with each year's amount sized to stay inside a chosen tax bracket. Spreading it out avoids pushing a large single conversion into high brackets, and over time it moves money out of accounts that will later force required minimum distributions.
Why are the years between retiring and Social Security the right window?
In those years earned income has stopped, Social Security has not started, and required minimum distributions are still ahead, so taxable income is usually at a lifetime low. That leaves unused room in the lower brackets, and conversions fill it at a rate you may never see again. Once Social Security and RMDs arrive, that room disappears.
How does IRMAA affect a conversion ladder?
Medicare premiums are set using your income from two years earlier, so a conversion at 63 can raise your Part B and Part D premiums at 65. Crossing an IRMAA threshold is a cliff rather than a gradual increase: a dollar over the line raises the premium for the whole year. Conversions made well before 63 avoid it entirely, which is another reason to start the ladder early.
Which bracket should I fill?
There is no universal answer. Filling the 12% bracket is conservative and widely used. Filling the 22% or 24% bracket converts far more but only makes sense if you expect your later rate, including the survivor's single-filer rate, to be at least as high. The comparison that matters is the rate you pay now against the rate the money would face later, not the absolute tax bill.
Should I pay the conversion tax from the converted amount?
Paying from taxable savings rather than withholding from the conversion leaves more inside the Roth, which is where the tax-free growth happens, and avoids the penalty that can apply to withheld amounts before 59 and a half. It also means the conversion is only worth doing if you have outside cash to cover the bill.
planbend is a planning tool, not financial or tax advice. Bracket figures are 2026 federal estimates and change annually. Confirm with a tax professional before converting.