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Retirement Tax Stack Planner Calculator

Plan your pre-retirement Roth conversions by mapping tax bracket room, Medicare IRMAA exposure, Social Security taxation, and RMD pressure across five years.

Quick answer: Size a pre-retirement Roth conversion corridor across tax bracket room, IRMAA headroom, Social Security taxation, NIIT exposure, RMD pressure, and cash-bucket needs. Enter MAGI, taxable income, bracket ceiling, and IRMAA threshold to personalize the estimate. It returns Roth conversion corridor, IRMAA headroom, and 5-year plan so you can compare the impact before choosing a next step. Use it to compare long-term value, tax impact, risk, time horizon, and contribution choices.

SWReviewed by SwitchWize Research Desk · Last reviewed July 2, 2026
Estimated Conversion Ceiling Under Selected Thresholds
$73,000
Estimated Conversion Ceiling Under Selected Thresholds
$73,000
Years Until RMD Age
10.0 years
Federal Bracket Room
$86,775
IRMAA Headroom Before Conversion
$73,000
Rule-backed calculation
Supported · 2026

Engine retirement-tax-stack-2026 · us-federal-income-tax-2026@2026.1.0, us-federal-social-security-tax-2026@2026.1.0

Sources: Tax year 2026 inflation adjustments · Publication 915 — Social Security and Equivalent Railroad Retirement Benefits

  • Federal bracket room and taxable Social Security use the coordinated 2026 rule package; state, NIIT, and cash-bucket fields remain disclosed planning assumptions.
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Illustrative Half-Ceiling Scenario
$36,500
Estimated Tax on Ceiling Conversion
$17,520
5-Year Conversion Capacity
$365,000
Estimated First RMD
$35,849
Estimated Tax on First RMD
$10,396
Estimated Taxable Social Security
$35,700
NIIT Headroom After Conversion
$32,000
Target Cash Bucket
$156,000
Cash Bucket Gap
$66,000
Diagnostic

Your selected-threshold conversion range is $36,500 to $73,000, with $73,000 of IRMAA headroom before conversion.

Estimated first RMD is $35,849; this uses the RMD starting age you selected and should be reviewed before Medicare cliffs or Social Security taxation narrow the window.

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My retirement tax planning range is $36,500 to $73,000, with estimated first RMD of $35,849.

Retirement tax corridorConversion window open
Conversion corridor
$36,500 - $73,000
IRMAA headroom
$73,000
Estimated first RMD
$35,849
Cash bucket gap
$66,000
YearAge5-year tax-window plan
163$73,000 conversion target. Fill corridor, then recheck thresholds
264$73,000 conversion target. Fill corridor, then recheck thresholds
365$73,000 conversion target. Fill corridor, then recheck thresholds
466$73,000 conversion target. Fill corridor, then recheck thresholds
567$73,000 conversion target. Fill corridor, then recheck thresholds
Next best move

Use this as a planning corridor, then confirm current brackets, Medicare thresholds, and state tax before converting.

What to do next

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Your action plan
  1. 1

    Find the tax corridor

    Use bracket room and IRMAA headroom to estimate a Roth conversion range before changing accounts.

  2. 2

    Map the next five years

    Repeat the corridor annually before RMDs, Medicare cliffs, or Social Security taxation narrow the window.

  3. 3

    Verify with a tax professional

    Treat the output as an education-only planning range and confirm thresholds before converting.

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This is an educational estimate, not tax, legal, investment, or lending advice. Tax rules, rates, and eligibility change and depend on your full situation. Confirm with a qualified professional or the provider before acting.

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Build this retirement tax plan in Money MapSave the conversion corridor next to retirement income, cash, debt, and account decisions.
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Check the IRMAA cliffModel the first Medicare surcharge threshold before converting.
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Compare conversion timingTest whether converting now, partially, or later looks stronger.
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Estimate future RMD pressureSee how required distributions may change future taxable income.
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Layer in retirement incomeTranslate the tax plan into monthly spending and account withdrawals.
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Frequently Asked Questions

Everything you need to know.

What does an example Retirement Tax Stack Planner calculation look like?
Using this calculator's own default assumptions, current age of 63, applicable rmd starting age of 73 and current magi before conversion of 145,000 produces estimated conversion ceiling under selected thresholds of $73,000 and years until rmd age of 10.0 years. Enter your own numbers above to see how it changes for your situation.
Why does converting in retirement look different from converting before I start taking Social Security?
Once you claim Social Security, your Modified Adjusted Gross Income automatically includes half of benefits, which narrows your room to convert without triggering IRMAA surcharges or pushing more of your benefits into taxable income. Converting before you claim gives you a cleaner window to fill available tax bracket room without those dual income tests colliding.
How does a Roth conversion corridor affect my Required Minimum Distributions?
Converting traditional IRA assets to Roth reduces your traditional IRA balance and therefore lowers the RMD you must take each year after age 73. This creates a trade-off: you pay tax on the conversion now, but you shrink the income stream that will be forced upon you later, which can preserve more of your other income sources below IRMAA thresholds.
Is the Retirement Tax Stack Planner Calculator free to use?
Yes. SwitchWize calculators are free, and you do not need an account to run scenarios or view the result.
Does using the Retirement Tax Stack Planner Calculator affect my credit score?
No. Using a calculator does not trigger a credit check. A credit impact can occur only if you apply directly with a lender, card issuer, or provider.
Are the results personalized financial advice?
No. Calculator outputs are educational estimates based on the inputs you enter. Review assumptions and confirm terms directly with providers before making a financial decision.
What should I do after seeing the result?
Use the recommendation module on this page to build this in money map, or run Money Map to compare this investing & retirement decision with your other opportunities.
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Related offers are matched by the calculator surface (ira) and ranked using SwitchWize data such as rate, fees, trust signals, product fit, and switching friction. Paid relationships do not change organic ranking order.
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Rate and offer data is reviewed on a recurring cadence and every offer module shows review context or links to the methodology and disclosure pages.
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The SwitchWize methodology page explains how rate freshness, editorial review, affiliate disclosure, and category ranking factors work.
Can Money Map use this result?
Yes. Money Map is the broader diagnostic path: it compares savings, mortgage, cards, and debt so you can see whether this calculator result is your highest-impact next move.

Why This Matters

Converting traditional IRA assets to a Roth account creates taxable income that can trigger Medicare IRMAA surcharges, push Social Security into taxation, and accelerate RMD timelines. Timing conversions across a low-income window before retirement helps you lock in tax-free growth and reduce forced distributions later. This decision compounds over decades, so sizing your corridor now prevents costly cliffs after retirement.

How to Use It

  1. 1Enter your projected Modified Adjusted Gross Income, taxable income, and current IRA balance.
  2. 2Input your tax bracket ceiling and the Medicare IRMAA thresholds relevant to your filing status.
  3. 3Review your Roth conversion corridor, IRMAA headroom, and five-year projection to see where you have room to convert without triggering surcharges or pushing more Social Security income into taxation.
  4. 4Compare the RMD pressure and cash-bucket needs shown in the output to decide how much to convert each year.
  5. 5Take your results to a tax professional to verify alignment with your full financial picture.
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