Model
Strategy reference

Roth conversion — 10-year window

Balance trajectory

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Annual tax breakdown

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Per-year plan

Override global defaults per year · "Custom" unlocks direct conversion entry

Full breakdown

Retirement check — age 73

Strategy reference & constraints

Conversion strategies

24% Bracket
Fill MAGI to the top of the 24% bracket ($413K MFJ). The only strategy that meaningfully depletes a $3–4M pre-tax balance over a 10-year window. Recommended as the default. Effective all-in rate ~28–30% with CO tax.
22% Bracket
Fill to the 22% ceiling ($230K MFJ). Barely outpaces pre-tax growth at 7% nominal — depletion is modest. Useful in years with additional income sources consuming the bracket.
IRMAA Tier 1 Ceiling
Cap MAGI at $218K to avoid all IRMAA surcharges. Conservative — only meaningful if you're 63+ (2-yr lookback) and want zero Medicare surcharge. Pre-65 conversions have no IRMAA regardless.
IRMAA Tier 1 Breach
Allow MAGI to $276K — paying Tier 1 IRMAA ($2,296/yr couple) to get $58K more conversion than the Tier 1 Ceiling. Usually worth it: $58K × 8% bracket savings >> $2.3K surcharge.
NIIT Ceiling
Cap MAGI at $250K to avoid the 3.8% Net Investment Income Tax on LTCG. Only relevant when harvesting significant capital gains in the same year as conversions. The two largely compete — choose one.
0% LTCG Only
Stay under the 0% long-term capital gains threshold ($94K MFJ taxable income). Leaves almost no room for Roth conversion. Useful only in very early window years or when brokerage gain harvesting is the priority.
No Conversion
No Roth conversion — expenses and taxes funded from brokerage/pre-tax as needed. Pre-tax balance compounds. Useful for modeling baseline or years when large events (rental sale, inherited RMD cleanout) fill the bracket.
Custom
Enter a specific conversion amount directly. Use when you know the exact amount for a given year — e.g., deliberately converting into the 32% bracket for smoothing, or a partial-year window. Overrides all ceiling logic for that year.

Key thresholds (MFJ, 2026)

22% bracket top
Taxable income
$230,250 CPI indexed
24% bracket top
Taxable income
$413,100 CPI indexed
32% bracket top
Taxable income
$512,450 CPI indexed
0% LTCG ceiling
Taxable income
$94,050 CPI indexed
NIIT threshold
MAGI — Net Investment Income Tax 3.8%
$250,000 FROZEN
SS taxation threshold
Provisional income — 85% SS taxable above
$44,000 FROZEN
Standard deduction (65+)
MFJ, both 65+
$32,300 CPI indexed

IRMAA surcharges (MFJ, 2026 couple/yr)

≤ $218,000 MAGI
$0
$218K – $274K
Tier 1
$2,296 / yr
$274K – $342K
Tier 2
$6,068 / yr
$342K – $410K
Tier 3
$10,186 / yr
$410K – $750K
Tier 4
$14,304 / yr
IRMAA uses a 2-year income lookback — income at ages 63–64 determines surcharges at 65–66. Pre-65 conversions have zero IRMAA impact. IRMAA thresholds adjust partially with CPI but with lag and rounding — modeled as approximately stable in real terms.

Key dates & ages

Medicare eligibility
Age 65
IRMAA lookback window
Ages 63–64
SS earliest claim
Age 62 (reduced)
SS full retirement age
67 (born ≥1960)
SS maximum benefit
Age 70
RMD begins
Age 73
RMD divisor at 73
26.5 (Uniform Lifetime Table)
Roth 5-yr seasoning
Per conversion (earnings)
Inherited IRA depletion
10 years (non-spouse)

Inflation & real-terms notes

This model runs in nominal terms with an explicit inflation input. Real growth = nominal growth − inflation (Fisher approximation, error <0.15% at typical rates — negligible for planning). Setting inflation to 0% gives a real-terms model where all dollar amounts represent today's purchasing power.

CPI-indexed ceilings (tax brackets, standard deduction, LTCG thresholds) are scaled by the inflation rate when "Scale indexed ceilings" is toggled on. This correctly reflects that their real value stays roughly constant. With the toggle off, they remain at 2026 nominal values — conservative, since real bracket values rise with inflation.

Frozen thresholds (NIIT $250K, SS provisional income $44K) are never scaled — they are fixed in law. At 3% inflation over 10 years, the NIIT threshold in real terms erodes from $250K to $186K, meaning conversions that today clear the NIIT threshold will eventually hit it even at constant real income. This model flags when your MAGI ceiling approaches these frozen thresholds.

IRMAA thresholds receive partial CPI adjustment with lag and rounding. Modeled as scaled with inflation (conservative approximation). In practice they may lag slightly, underestimating surcharge exposure.