Retirement "What If" Tax Planner — CA + FederalScenarios compared: Just-retired / 1-SS / 2-SS Pre-RMD / RMD Phase | MFJ Filing Status | California Resident
Retirement "What If" Scenarios - Enter approx values of incomes and see how taxes work out
IRMAA impact = Tax Year + 2
ⓘ SS excluded from CA income · LTCG at ordinary CA rates
ⓘ IRMAA uses 2-yr lookback — this year's AGI affects premiums in Tax Year + 2
Scenario 1 · Roth Conversion + 401k Withdrawal
— Income Summary —
Total Income
—
Provisional Income
—
Taxable SS
—
— Federal —
Federal AGI
—
Std Deduction
—
Ord Taxable Inc
—
Fed Ordinary Tax
—
Fed LTCG Tax
—
NIIT (3.8%)
—
Fed Total Tax
—
Marginal Bracket
—
Headroom → Next
—
Fed Eff Rate
—
— IRMAA (Medicare) —
IRMAA Tier
—
Surcharge/yr
—
IRMAA Applies In
—
— California —
CA Adj Income
—
CA Itemized Ded
—
CA Taxable Inc
—
CA Tax (Gross)
—
Exempt Credit
—
CA Tax (Net)
—
CA Marginal
—
CA Eff Rate
—
Total Tax (Fed + CA)
—
—
Net Take-Home
—
Scenario 2 · Roth Conversion + 1 SS Income
— Income Summary —
Total Income
—
Provisional Income
—
Taxable SS
—
— Federal —
Federal AGI
—
Std Deduction
—
Ord Taxable Inc
—
Fed Ordinary Tax
—
Fed LTCG Tax
—
NIIT (3.8%)
—
Fed Total Tax
—
Marginal Bracket
—
Headroom → Next
—
Fed Eff Rate
—
— IRMAA (Medicare) —
IRMAA Tier
—
Surcharge/yr
—
IRMAA Applies In
—
— California —
CA Adj Income
—
CA Itemized Ded
—
CA Taxable Inc
—
CA Tax (Gross)
—
Exempt Credit
—
CA Tax (Net)
—
CA Marginal
—
CA Eff Rate
—
Total Tax (Fed + CA)
—
—
Net Take-Home
—
Scenario 3 · Roth Conversion + 2 SS (Pre-RMD)
— Income Summary —
Total Income
—
Provisional Income
—
Taxable SS
—
— Federal —
Federal AGI
—
Std Deduction
—
Ord Taxable Inc
—
Fed Ordinary Tax
—
Fed LTCG Tax
—
NIIT (3.8%)
—
Fed Total Tax
—
Marginal Bracket
—
Headroom → Next
—
Fed Eff Rate
—
— IRMAA (Medicare) —
IRMAA Tier
—
Surcharge/yr
—
IRMAA Applies In
—
— California —
CA Adj Income
—
CA Itemized Ded
—
CA Taxable Inc
—
CA Tax (Gross)
—
Exempt Credit
—
CA Tax (Net)
—
CA Marginal
—
CA Eff Rate
—
Total Tax (Fed + CA)
—
—
Net Take-Home
—
Scenario 4 · RMD + 2 SS Incomes
— Income Summary —
Total Income
—
Provisional Income
—
Taxable SS
—
— Federal —
Federal AGI
—
Std Deduction
—
Ord Taxable Inc
—
Fed Ordinary Tax
—
Fed LTCG Tax
—
NIIT (3.8%)
—
Fed Total Tax
—
Marginal Bracket
—
Headroom → Next
—
Fed Eff Rate
—
— IRMAA (Medicare) —
IRMAA Tier
—
Surcharge/yr
—
IRMAA Applies In
—
— California —
CA Adj Income
—
CA Itemized Ded
—
CA Taxable Inc
—
CA Tax (Gross)
—
Exempt Credit
—
CA Tax (Net)
—
CA Marginal
—
CA Eff Rate
—
Total Tax (Fed + CA)
—
—
Net Take-Home
—
Tax Breakdown by Scenario
🔍 Roth Conversion Optimizer — Find the Sweet Spot
Base Income (non-conversion sources)
Conversion Range
$100,000
ⓘ Vertical dashed lines = federal bracket boundaries & IRMAA thresholds
ⓘ Gold line = total tax (Fed+CA). Blue line = IRMAA annual surcharge (couple).
ⓘ Optimal conversion fills your current bracket without crossing into the next.
⚖️ Break-Even Roth Conversion Analysis
Conversion Parameters
Run calculation…
ⓘ Green = cumulative Roth advantage (after upfront tax opportunity cost).
ⓘ Break-even = year the line crosses zero. Positive = Roth ahead, Negative = traditional still better.
ⓘ Opportunity cost = upfront tax amount invested in taxable account at "Taxable Acct Return".
Tax Engine — Key Rules
✓ Federal brackets: 2026 MFJ projected · SS taxability: full IRS two-tier worksheet ($32k/$44k PI thresholds) ·
LTCG: preferential rates (0/15/20%) stacked on ordinary taxable income ·
NIIT: 3.8% on investment income when MAGI > $250k (MFJ) ·
IRMAA: 2025 MFJ brackets, 2-year lookback (this year's AGI → Medicare premiums in Tax Year + 2) ·
California: SS fully excluded · LTCG at ordinary CA rates · 10 CA brackets · effective rates on AGI
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