Does this handle tax brackets?

No. It uses a single marginal rate for simplicity. Use your top marginal rate or run multiple scenarios for different brackets.

Are state taxes included?

Only if you include them in the marginal rates you enter.

Does this model RMDs or Social Security taxation?

No. It’s a quick snapshot. Use a full planner for RMDs, SS taxation, and deductions.

Can I model partial conversions over years?

Enter each year’s conversion amount separately and adjust years until retirement accordingly.

Is the future rate guaranteed?

No. Tax law can change. Run best/worst-case rates to bracket your decision.

finance calculator

Roth Conversion Tax Calculator

Estimate tax owed on a Roth conversion now versus potential tax later if you leave funds in a traditional account.

Results

Tax owed on conversion now: $4,400
Future Roth balance (tax-free): $53,066
Estimated tax if left traditional: $12,736
Estimated tax saved vs keeping traditional: $8,336

How to use this calculator

Enter the amount you plan to convert.
Set current marginal tax rate, expected future rate, and growth assumptions.
Review tax owed now, estimated future tax if left traditional, and the net tax difference.

Inputs explained

Current marginal rate: Your top marginal rate this year; drives the tax owed on the conversion.
Expected future tax rate: Your anticipated marginal rate in retirement if funds stay traditional (federal + state if relevant).
Assumed annual return: Growth rate applied to the converted amount until retirement.
Years until retirement: Number of years the money compounds before withdrawals.

How it works

Tax now = conversion amount × current marginal rate.

Future balance assumes compounding at your chosen return. Tax later = future balance × expected future rate (if left traditional).

Estimated tax benefit = tax later − tax now; positive means converting could reduce lifetime taxes under these assumptions.

Formula

Tax now = Conversion × Current rate
Future balance = Conversion × (1 + r)^years
Tax later (if traditional) = Future balance × Future rate
Estimated tax benefit = Tax later − Tax now

When to use it

Checking if converting during a low-income year could save taxes.
Comparing today’s marginal rate to expected retirement rates.
Modeling conversions across multiple years to fill lower tax brackets.

Tips & cautions

Watch IRMAA/phaseouts—large conversions can raise Medicare premiums or trigger credits phaseouts.
Spread conversions over multiple years to avoid jumping brackets.
State taxes matter; include them in your marginal rate if applicable.
Simplified; does not model bracket stacking, deductions, or Social Security taxation.
Ignores RMD rules and the impact of conversions on other income-based thresholds.
Assumes a constant return; markets and tax law can change.

Worked examples

$20k conversion, 22% now, 24% later, 5% for 20 years

Tax now = $20,000 × 22% = $4,400
Future balance ≈ $53,099
Tax later = $53,099 × 24% ≈ $12,744
Estimated tax benefit ≈ $8,344

$30k conversion, 24% now, 22% later, 5% for 15 years

Tax now = $30,000 × 24% = $7,200
Future balance ≈ $62,468
Tax later = $62,468 × 22% ≈ $13,743
Estimated tax benefit ≈ $6,543

Deep dive

Estimate the tax bill for a Roth conversion and compare it to the tax you’d owe later if you keep funds in a traditional account.

Enter conversion amount, current and future marginal tax rates, expected return, and years to see whether a conversion could reduce lifetime taxes.

FAQs

Does this handle tax brackets?: No. It uses a single marginal rate for simplicity. Use your top marginal rate or run multiple scenarios for different brackets.
Are state taxes included?: Only if you include them in the marginal rates you enter.
Does this model RMDs or Social Security taxation?: No. It’s a quick snapshot. Use a full planner for RMDs, SS taxation, and deductions.
Can I model partial conversions over years?: Enter each year’s conversion amount separately and adjust years until retirement accordingly.
Is the future rate guaranteed?: No. Tax law can change. Run best/worst-case rates to bracket your decision.

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For informational planning only. Roth conversions can affect brackets, credits, IRMAA, and state taxes. Consult a tax professional before converting.