Tax · super (composes 3 primitives)
Roth conversion ladder
Type your Traditional IRA balance, expected income window, and target marginal rate. We chain the optimal annual conversion (filling brackets), the 5-yr seasoning timeline, the per-year tax cost, and the lifetime tax savings vs leaving it traditional and paying RMD income tax.
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Inputs
Result
Convert $206,700/yr × 18 yrs → $3,720,600 total. Tax cost $635,436 now vs $1,190,592 at RMD. Save $555,156.
Strong move: $555,156 of lifetime tax savings. Coordinate with ACA subsidies if applicable — a big conversion can blow the cliff and cost you 2-4× the savings.
- 1
Room in the 22% bracket
$206,700
Top of bracket $206,700 − taxable other income $0
- 2
Blended tax rate on conversion
17.1%
Spreads across whatever brackets the conversion crosses
- 3
Annual tax cost of conversion
$35,302
$206,700 × 17.1%
- 4
Conversion window (5-yr season + before RMD)
18 years (ages 52 → 70)
Each contribution must season 5 years before tax-free withdrawal under 59½. After 59½, only the 5-yr clock for QBE applies.
- 5
Total amount moved to Roth
$3,720,600
$206,700 × 18 years
- 6
Total conversion tax (paid during window)
$635,436
- 7
RMD tax avoided
$1,190,592
If you don't convert: $3,720,600 stays Traditional, taxed at 32% marginal in retirement
Stand-alone calc - 8
Lifetime tax delta
$555,156
Convert wins — pay lower rate now, save higher rate later
- 9
Bonus: Roth grows tax-free
$1,674,270
Plus reduced future RMD-bracket creep if your spouse outlives you (single-filer brackets)
Assumptions & notes
- 5-year seasoning is per-conversion. Each year's conversion has its own 5-year clock before that money can be withdrawn tax-free if under 59½.
- After 59½ + a 5-year clock on ANY Roth → fully tax-free. The 5-yr-per-conversion only matters if accessing under 59½.
- ACA premium subsidies cliff at 400% of FPL. Monitor MAGI when converting; one extra dollar of MAGI can cost you the subsidy.
- State tax matters — high-tax-state retirees moving to a no-tax state should convert AFTER the move.
Multi-scenario comparison
What if — ±20% on one input
| Scenario | Current Traditional IRA / 401(k) balance | Headline | Δ vs baseline | Magnitude |
|---|---|---|---|---|
| −20% (cautious) | $384,000 | Convert $206,700/yr × 18 yrs → $3,720,600 total. Tax cost $635,436 now vs $1,190,592 at RMD. Save $555,156. | 0 | |
| Baseline | $480,000 | Convert $206,700/yr × 18 yrs → $3,720,600 total. Tax cost $635,436 now vs $1,190,592 at RMD. Save $555,156. | 0 | |
| +20% (aggressive) | $576,000 | Convert $206,700/yr × 18 yrs → $3,720,600 total. Tax cost $635,436 now vs $1,190,592 at RMD. Save $555,156. | 0 |
Try the input with the highest sensitivity (above). The Δ column shows the dollar swing from a 20% move — that's how much room you have for a counter, raise, or hedge.
Goal seek
Solve for an input value
Pick the input you want to vary and the output you care about. We'll find the input value that gets you to the target. Bisection-based; converges in < 50 iterations.
Monte Carlo simulation
Distribution under input uncertainty (500 trials)
We perturb every numeric input with normal-distributed noise (10–25% sigma depending on input type) and run 500 compute trials. The output is a probability distribution, not a single number — closer to how finance actually works.
Most-leveraged inputs (sensitivity analysis)
Where to focus — what moves the answer most
Each input perturbed ±10%; measured impact on Room in the 22% bracket. Higher elasticity = bigger lever.
- 1
Current Traditional IRA / 401(k) balance
Elasticity ↕ 0.00× — 10% change in this input affects Room in the 22% bracket by 0.0%.
- 2
Current age
Elasticity ↕ 0.00× — 10% change in this input affects Room in the 22% bracket by 0.0%.
- 3
RMD start age
Elasticity ↕ 0.00× — 10% change in this input affects Room in the 22% bracket by 0.0%.
- 4
Other annual income during conversion window
Elasticity ↕ 0.00× — 10% change in this input affects Room in the 22% bracket by 0.0%.
ShowMath is the only calc site that surfaces this. Adjust the highest-leverage input first — that's where small moves create big results.
Chain payload (for the 3D constellation)
{
"slug": "roth-conversion-ladder",
"depth": 1,
"primitives": [
"roth-conversion-calculator",
"rmd-calculator",
"tax-bracket-calculator"
],
"composes": [],
"chain": [
{
"key": "bracket_room",
"label": "Room in the 22% bracket",
"primitive": "tax-bracket-calculator",
"numeric": 206700
},
{
"key": "blended_rate",
"label": "Blended tax rate on conversion",
"numeric": 17.07885824866957
},
{
"key": "annual_tax_cost",
"label": "Annual tax cost of conversion",
"numeric": 35302
},
{
"key": "conversion_window",
"label": "Conversion window (5-yr season + before RMD)",
"numeric": 18
},
{
"key": "total_converted",
"label": "Total amount moved to Roth",
"primitive": "roth-conversion-calculator",
"numeric": 3720600
},
{
"key": "total_tax_now",
"label": "Total conversion tax (paid during window)",
"numeric": 635436
},
{
"key": "rmd_tax_avoided",
"label": "RMD tax avoided",
"primitive": "rmd-calculator",
"numeric": 1190592
},
{
"key": "lifetime_savings",
"label": "Lifetime tax delta",
"numeric": 555156
},
{
"key": "roth_growth_benefit",
"label": "Bonus: Roth grows tax-free",
"numeric": 1674270
}
]
}The chain explained
Each step above corresponds to a primitive calculator. Click any to see the stand-alone version with its own explainer + sources.
- roth conversion calculatorshipping soon
- rmd calculator
- tax bracket calculatorshipping soon
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