Should you convert part of your traditional IRA to a Roth? This calculator estimates the tax cost today, projects the growth of both paths, and shows whether converting comes out ahead over time. Uses 2026 federal tax brackets.
A Roth conversion moves money from a traditional IRA (pre-tax) to a Roth IRA (after-tax). You pay income tax on the converted amount now, but all future growth is tax-free. The question is whether paying tax today beats paying tax later.
This calculator compares two scenarios. In the “convert” path, you pay federal and state tax on the conversion amount at your current marginal rates, then the remaining balance grows tax-free for the number of years you specify. In the “don’t convert” path, the full amount grows pre-tax, but you pay income tax at your expected retirement bracket when you eventually withdraw.
The net benefit depends on three things: (1) how your current tax rate compares to your future rate, (2) how many years the Roth has to grow tax-free, and (3) whether the conversion triggers IRMAA surcharges on your Medicare premiums. Conversions tend to be most valuable in low-income years between retirement and age 72, before RMDs begin.
The calculator assumes a 6% annual growth rate for both paths and uses 2026 federal tax brackets. It does not account for the standard deduction, itemized deductions, or other credits. Your actual tax situation may differ.
Roth conversions are subject to a 5-year holding period. If you withdraw converted funds within 5 years of the conversion and you are under age 59 1/2, you may owe a 10% early withdrawal penalty on the converted amount (though not on earnings, which have their own 5-year rule). Each conversion starts its own 5-year clock. This calculator does not model early withdrawal penalties, so plan your conversion timing accordingly.
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