Roth Conversion Optimizer

Converting to Roth means paying tax now for tax-free growth later. See whether it pays off given your rates and horizon.

Your numbers

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Roth advantage

Extra after-tax dollars
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Converting pays tax now at your current rate, then the Roth grows tax-free. Leaving the money in a traditional IRA defers tax but taxes the entire balance at withdrawal. When your retirement rate is higher than today's, converting usually wins. Paying the conversion tax from outside funds (not the IRA) improves the result further. Consult a tax advisor.
About this calculator

Roth Conversion Optimizer

Compares paying tax now to convert to a Roth IRA against leaving funds in a traditional IRA and paying tax at withdrawal.

The core tradeoff

A Roth conversion means paying income tax today on the converted amount so the money then grows and is withdrawn tax-free. Leaving the money in a traditional IRA lets the full pre-tax balance grow, but every dollar withdrawn later is taxed at your future rate. Conversions tend to win when your tax rate in retirement is expected to be equal to or higher than today's rate.

What the model leaves out

This calculator compares after-tax ending values over your chosen horizon using a single growth rate for both paths. It does not model paying the conversion tax from outside funds, required minimum distributions, IRMAA surcharges, or state taxes, all of which can shift the decision. A large conversion can also push you into a higher bracket in the conversion year, so coordinate with a tax professional; this is not tax advice.

How to use it

  1. Enter the amount you plan to convert.
  2. Set your current marginal tax rate.
  3. Enter your expected tax rate in retirement.
  4. Add years until withdrawal and an annual growth rate to compare outcomes.

Frequently asked questions

When does a Roth conversion make the most sense?

It is most attractive when you expect a higher or equal tax rate later and can pay the tax from non-retirement funds. Low-income years, such as early retirement before Social Security, are common opportunities.

Can I undo a conversion?

No, recharacterizing a Roth conversion has not been allowed since 2018, so the decision is permanent. Plan the amount carefully before converting.

Does converting affect other taxes?

Yes, the added income can raise Medicare IRMAA surcharges and the taxable share of Social Security. Consider the full-year picture before converting.

See the exact formula and a worked example on our methodology page.

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